Most judges will want to consider what a mature, articulate 10 year old has to say about her living arrangements and her preferences to live with another parent. The child's preference is not necessarily the final word at the age of 10, but it will be given considerable weight. What this means is that if your child clearly and consistently expresses a desire to live with you and her sibling, you should have this documented by a therapist or law guardian for the child. You should file a petition in Family Court and appear with a lawyer on the court date. You should encourage the child's relationship with the other parent and make that a priority. Both parents should be realistic about what the child wants and needs. In a sense, the transfer of custody will become inevitable if the child really desires it, and the parents should keep that in mind.
There are many issues raised by your narrative. How you act and relate wqith the older child has no bearing on what should happen with the 10 year old going to her dad's place.You seem to be relating properly with the 12 year old who lives primarily at her dad's residence. It sounds to me like everyone needs to be involved in family therapy so that a trained therapist can work through the conflicts with each parent and with each child.
Let me spend some time explaining how a court "listens" to what a minor child wants and how well it is expressed. Children as young as seven are able to express a preference, but only if the child is mature and specific about her desires and has good reasons for coming to the conclusions expressed. As a child gets older, and more mature, and maturity rather than chronological age is the important factor, the court gives greater weight to the child's expressed desires. When a child reaches 16 or so, unless the child comes off as very immature, the court will almost always go along with the child's wishes, unless it is clearly not in the child's best interest to do so. How mature is your child? What is the court liable to do with her opinion? One way to find out is to discuss the child's maturity with the pediatrician as a first step. Then you can ask the court to have a court mediator interview the child and report back to the court. In some cases, you can ask the court to appoint an attorney for the child, though in these tougher econo0mic times the court doesn't have the resources to pay for child's counsel and so the bill is often passed on to the parents.
I realize this is a little long, but it should give you a bit of an idea of the process. You are best to diuscuss these matters with an attorney in your area. You might try clicking on http://courts.ky.gov/stateprograms/divorceeducation/contactdivorceeducation.htm and contacting the Program Coordinator of Pike County's Divorce Education program to help find resources in your area. Good luck to you asnd your children.
Since it would be inefficient and probably unhelpful to address the specific nuances of your perspective of this case, I will respond to your main inquiry only. Each state has different statutory and case law as to what age and maturity level entitles/requires a court to listen to a child's point of view regarding custody preferences. Each judge has different procedures as to whether he or she will hear fromthe child in court or in chambers, with the attorneys and/or parties present, and whether the child's position is even relevant. For example, in PA, I have had a Judge talk to a 6 year old boy in a Relocation case and a different Judge refuse to meet with a 14 year old boy in a Visitation case.
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