My 2 year old son's father hasn't seen him in over a year. He does pay child support but only because it's garnished. Would that that length of time still be considered abdonment even though he does pay CS?

Also, my son's father also has two other children living in MN. He is ordered to pay them $1,700.00 a month for BOTH children. My son (in Oklahoma) gets $250.00 a month. Is there anything (like a law) between states for equal support payments? I hope that makes sense!