Is this a Material Change is Circumstance?

[Justabovewater]

My son Turned 18 in November. He decided he wanted to go live with his Mother because I Grounded him for having bad grades his Senior year of High School. I am rather Strict on Grades but when he is a Senior and Failing, I feel like it is my responsibility as a Parent to get him Graduated. Anyway, We also have a 13 Year old Daughter that I have custody of. The Mother had her Attorney Contact my Attorney and request a Modification for the 13 year old to live with her Because the Children to to be in the same home. 1) When a Child turn 18 he becomes and Adult, It was his Choice to move out and I dont think this has anything to do with the 13 year old.  2) Him turning 18 and Moving was part of the Plan from Birth, IF he is 21, Married with Children, Would she still want them to be together? 3) I dont think him Turning 18 is a Material Change in Circumstance for a Change in Custody. Whats your thoughts?

[ocean]

What is your state say about child support ages? NY is to 21 so he mom could ask for child support for him (but you have the other child so....depending on salaries can negate child support). If you are in state that is 18, I agree with you , try to dismiss the case as son is now emancipated due to his age (but some states say 18 or graduate high school). Is he is school at mom's?  The 13 year old is in school and adjusted so as long as 13 doesn't start asking to go live with mom it should be fine. Around 13 is when judges MAY ask for their opinion. Does 13 yr old want to go with mom?

[Justabovewater]

Im in Kansas so 18 is the Legal age to become an adult. The Custody order says after Graduation is when child support is suppose to cease. She is also trying to get the Child Support ordered changes. He graduates in May, It will be well after that before we can get a court date. The child support is very little so I dont have a problem with letting her keep that. 

The 13 Year old is doing great is school, She does not want to go live with her mom because of friends in school and so forth. The children are very close so this may be enough to change her mind, and Mother has been putting stuff in her head as well.

[ocean]

Def go see a lawyer near you , you can even pull that mom is trying to child support shop to a state that is to 21. You may have a change to get it dismissed in NY. Do you have a court date in NY? What county?
Like you said this will def be dragged out passed May but usually orders go by date of filing. Will son even graduate on time with her if he was failing by you? Call the new school and get on parent portal if they have it and can track attendance/grades.