Should my husband modify his court order so that his son can live with us?

He pays child support and the court order has my husband getting him every other weekend, every other holiday and claim him on his taxes every other year. He has his own room here and siblings. Last year she was having a hard time paying daycare, my husband agreed to pay half of child care as well as child support as long as he could get him every other week. We later on found out the grandmother was paying her half and this was a verbal agreement she broke as soon as the state stepped in to pay child care and she claimed him on her taxes. On top of this it wasn't her year to claim him. So about 6 months ago she had to live with her mom we found out about 5 months ago and found out last week she owes daycare almost a grand. She's not getting a tax return for being penalized from last year. Now she wants him to pay 200$ for two months on top of child support and my step son will live with us for the two months. A verbal agreement would only be temporary and so we want to go to court and have him more. We want him two weeks out of the month and we want to pay half of child care and that's it. Do anyone have any legal advise for us?