joint legal custody and child support concerns

[kellybaron]

My friend has an 11 year old daughter and shares joint physical and legal custody with her mother. Her mother and he are preparing to go to court due to a disagreement on where she should attend school since they live in different districts. The school he is proposing has better test scores, smaller class sizes, and, in our opinion, offers a better educational experience for his daughter. Her mother wants her to attend another school due to the fact it is closer and she has a few freinds attending. She is now also asking for sole legal custody claiming that my friend is negligent in his responsibility toward their daughter's social and emotional well being. She is also asking the courts to allow her to claim their daughter on her income tax returns even though they split their time with their daughter equally and my friend is responsible for 70% of her living expenses. My question is...how solid is her case against him for the sole legal custody based only upon this current dispute and are their any federal regulations or laws that support his case that he should be able to claim her on yearly taxes since he is responsible for the majority of her financial care?