When parents separate, the separation itself can be so difficult for the adults, it becomes hard to keep focused on what is best for any child(ren) they may have.
One reason for this is that couples seldom reach the conclusion that the relationship is over at the same time. Below is a simple illustration that shows how the one who leaves (A) generally has a different experience to the one who is left (B); or at least the two parents usually experiences the roller coaster of emotions at slightly different times.

This difference can make the process of discussing how they are going to be parents now they are no longer partners challenging, to say the least!
Because such separations are nothing new, there is a great deal of research and various ways of describing common roles separated parents often play. The simplest just has three categories:
Disengaged parents
These parents avoid contact to avoid conflict. They are likely to communicate
by email or text about the children’s arrangements
Parallel parents
These parents run separate lives with their children and only communicate
when something really important comes up. They do not criticise each other
in front of the children, and do not use the children to send messages to
each other.
Cooperative parents
These parents cooperate in a business like manner, sharing parenting. They
are likely to have similar values and parenting styles, and are able to
discuss issues and resolve differences by focusing on the needs of their
children.
Another way of looking at how parents evolve after separation uses five distinct ways. The following is adapted from Michael Scott’s excellent article:
Dissolved Duos
These parents have reached such an extreme point of pain that one of the
parents drops out of the child’s life entirely. The parent typically
moves away and begins a new family, often never even telling the new spouse
that there had ever been another family. This parent would not have even
known that their child had graduated. Departing is one way to disengage
from the emotional pain of divorce, but the price that the child pays in
being abandoned can be huge.
Fiery Foes
These parents have such disdain for one another that, for example, one of
the parents cannot even attend the child’s graduation if the other
parent is present. Not only does each parent dislike the other, but the
child and the eventual grandchild will have to carry the anger down through
the generations as to how awful the other parent was as a parent, partner,
and yes, human being. The therapist of this child can do nothing more than
comfort the child during the therapy sessions. For, after these sessions,
the child must return to the family war. The children of these parents suffer
psychopathology of the worst order, distress that will assure them of the
need for life-long psychotherapy. Often the risks (both physical and emotional)
to the child of on-going efforts by their parents at co-parenting are too
great. Decisive and sometimes dramatic Court intervention is a virtual necessity
with Fiery Foes.
Angry Associates
Angry Associates do not know how to emotionally disengage from each other.
They are “compatible combatants.” They fight well together and
thus remain in a destructive relationship from which at least one of the
parties was truly attempting to leave. At least one of the partners gets
stuck in the emotional process of divorce and cannot move on with life.
This can go on for years or, perhaps, a lifetime. These parents are in a
persistent and continual power struggle with one another. They regularly
require third party intervention (mediators, lawyers, arbitrators, and judges).
They do not respect each other as parents, nor as people. Their child becomes
a pawn in this unrelenting conflict and his or her childhood is sacrificed
to the immaturity of the parents. These are the parents who do not encourage
the child to share time with the other parent. Involvement with extended
family members is not often a real possibility for the child.
Cooperative Colleagues
Cooperative Colleagues have a difficult time when they separate. They most
likely have attorneys or require a third party to assist in finalizing plans
of the marital settlement. Most often these people did not make a mutual
decision to separate. They still do not necessarily like each other, but
they respect one another as parents. They can separate their parenting from
their partnering issues. They support the child’s involvement in each
other’s lives and in the lives of the extended families. They are
generally courteous to each other. A few times a year, they may have a disagreement
that initially will require third party intervention, but they are able
to resolve such disputes outside of Court.
Eventually, cooperative colleagues figure out how to avoid getting caught
up in the drama of the former partner. At graduation, for example, they
may or may not sit together. Either way, they are cordial and not overtly
hostile. They will likely feel more comfortable purchasing separate gifts
for their child and one might take the graduate to dinner while the other
takes him or her to breakfast. These people have let go of each other. They
permit and support the child having a relationship with the other parent.
As years move on, each is less threatened by the other. The child has two
houses and two families under one large conceptual family umbrella.
Perfect Pals
Perfect Pals are best friends who were married and have made a mutual decision
to go their separate ways. These parents like one another. They usually
do all their own legal work and establish a parenting plan that is in the
“best interests of the child.” They are flexible and have respect
for each other, both as co-parents and as friends. These are the individuals
who will be able to celebrate holidays together. Even after remarriage to
others, they may, for example, all celebrate Thanksgiving dinner together.
When graduation comes, they might purchase one present together for their
child and sit together at the ceremony.
If you are a parent who would like to do the best you can for your children following a separation, a family mediator may be able to help you and your co parent sort out some practical arrangements. Give William a call on (09) 413 9940.
Day-to-day care and contact (custody and access)
The Care of Children Act 2004 introduced changes to terms used around the
custody and access of children. ‘Custody’ is now called ‘day-to-day
care’, while ‘access’ is now called ‘contact’.
When considering the care of their children, parents sometimes think of
their custody rights in respect of their children, of full custody or sole
custody. This language is no longer used by the Family Court. Care arrangements
for children are now called "parenting" and involved day-to-day
care, contact, and shared care.
The Care of Children Act 2004 also sets out some responsibilities that BOTH parents have at section 5 (I have bolded two sections I find parents sometimes need to be reminded of):
Principles relating to child’s welfare and best interests
The principles relating to a child’s welfare and best interests are
that¬
(a) a child’s safety must be protected and, in particular, a child
must be protected from all forms of violence (as defined in section 3(2)
to (5) of the Domestic Violence Act 1995) from all persons, including members
of the child’s family, family group, whanau, hapu, and iwi:
(b) a child’s care, development, and upbringing should be primarily
the responsibility of his or her parents and guardians:
(c) a child’s care, development, and upbringing should be facilitated
by ongoing consultation and co-operation between his or her parents,
guardians, and any other person having a role in his or her care
under a parenting or guardianship order:
(d) a child should have continuity in his or her care, devel¬opment,
and upbringing:
(e) a child should continue to have a relationship with both of
his or her parents, and that a child’s relationship with
his or her family group, whanau, hapu, or iwi should be preserved and strengthened:
(f) a child’s identity (including, without limitation, his or her
culture, language, and religious denomination and practice) should be preserved
and strengthened.
What is shared care in a Family Court parenting order?
"Shared care" is a term used in the Family Court to refer to a
variety of care arrangements for children. It may, or may not involve 50/50
shared care of the children.
IRD & WINZ
The Family Court is different from both the Inland Revenue Department and
Work and Income who deem care of a child to be shared if a parent cares
for a child for at least 40% of the nights (146 nights) of the child support
year (usually from 1 April to 31 March). The word “night” has
its usual meaning—it is simply the time between evening and morning,
from one day to the next.
In some situations a person might not care for a child for 40% or more of
the nights, but special circumstances exist that may mean the ongoing daily
care of the child is shared substantially equally between the two carers.
Consideration will be given to recognising shared care in these situations
on a case-by-case basis. The following situations may be considered as special
circumstances and treated as a shared care arrangement. One person can’t
care for the child overnight but looks after them every day. One person
looks after the child for slightly fewer than the minimum number of nights
(146 nights or 40% of the time), but also provides extensive daytime care
and extras, such as health care, school fees, uniforms, and sporting fees.
The Guardianship Act 1968.
Sets out The legal rules for guardianship, custody, and access in respect
of children and young people
The overriding principle: Welfare of the child
Under the Act the welfare of the child must always be the first and the
paramount consideration in guardianship, custody and access matters.
Guardianship begins when the child is born and ends on his or her 20th birthday,
unless the child marries before that age. More here.
What is 'Custody'?
Under the Act, custody is defined as the right to possession and care of
a child. In practical terms, this means the day-to-day care of the child.
Both parents usually have custody rights, but if they separate the Family
Court can grant a custody order in favour of just one of them if necessary.
The Court can also decide to make a joint custody order in favour of both
parents.
A parent, step-parent or guardian may apply to be granted custody. Other
people need the permission of the Court before they can apply for custody.
Once a young person reaches 16, custody orders no longer apply, unless there
are special circumstances.
Access
In the context of the Guardianship Act, the term access is only relevant
where custody has been given to one parent.
Access in these situations refers to the arrangements for a child or young
person to spend time with their non-custodial parent.
The parent who does not have custody may apply to the Court for an access
order so that the arrangements have legal weight.
The rights of other relatives such as grandparents or aunts/ uncles to be
granted access are limited to situations where one parent has died or has
been refused access or is not exercising access to the child.
Some useful links for thinking about parenting plans:
This is the Parenting Plan booklet prepared by the NZ Government. I think it has some great questions to help parents figure out how they are going to look after the children after separation
Here is a link to the same plan, but in MS Word format, so you can put in your children's names and edit it to make it more appropriate for you.
This is a link to information about the "Parenting Through Separation" programme
This page suggests different plans according to the roles listed above
This is quite a detailed explanation of high conflcit families and what happens within them
An acocunt of research into post separation parenting
Infants and overnight care – post separation and divorce
Children and Divorce - Helping Kids Cope with Separation and Divorce
A practical book: The CoParenting Toolkit