I have a daughter turning 16 in a month I am paying child support for all 3 my oldest wants to come home when she's 16 in a month will I only have to pay for the 2 younger ones if my oldest lives with me? They all live with their grandmother but my oldest is coming home in a month would the payments stop for my oldest?

Will you be going to court for a change in custody ? If not then you still owe regardless of where she lives.

First, if grandma has custody your oldest just can 't come home. You have to petition the court for a change of custody. The court will then decide whether she can move in with your or not. If the court allows it, then they should also modify the support agreement.