Custody & support

My husband and I are going through a divorce. We are getting along great, his parents are the problem. My soon to be ex has moved to Montana for a couple of months and will return this upcoming summer. He left his 14 year old son with his mom and dad (grandparents) until he returns. He informed them of his move before hand and offered his son a chance to go with him. Because of school and friends, he chose not to. My ex has been in Montana since October of this year. He just received a summons to appear in court where his parents are going after child support from him on his own child. They are doing this because the are mad about other financial situations that involve me. IF they do not have custody, can the legally go after child support? Also, can they obtain custody without his fathers permission. Please help us!

Yes, they can seek child support if the children are living with them, even without formal custody. If a child is living with you under an informal custody arrangement, you are still eligible to receive child support from the parent(s).