Split custody is rare, as it is thought that it is in the best to keep siblings together for mutual comfort, stability and support.
Reasons for split custody can be child preferences for different parents or siblings that do not get along with each other.
It is more common for older compared to younger siblings, and then usually at the request of one of the children.
One criticism of split custody is the same as for sole custody, in that the children only have one primary parent, which has been shown to cause worse physical, mental and social outcomes versus shared parenting.
[4][5][6] Split custody has also been criticized for separating siblings and limiting the amount of comfort, support and stability that they can give to each other.