no
Yes signing over custody is not the same as giving up your parental rights. You still have the right to visitation for example.
Custody, not parental rights.
has no jurisdiction to do so.
If you're referencing a custody change, you need power of attorney.
yes you do have to have full legal rights to sign over custody.
well i was looking to see how signing over my parental right works in Oklahoma
What rights are you talking about? Are they parents? To give the 19yo custody or terminate the 15yo parental rights you have to go to court to do so. The 19yo have to petition for custody.
see related question
Yes, unless/until the child is adopted.
If you sign over your parental rights do you still have to pay childsupport
No. If the court allows him to give them up, which they would not in this case, the mother is the only one with parental rights. Parental rights is not something you can give away or pass around to different people. As long as the mother is fit there is no way a grandparent would get custody.
In any case, you would have to go to court. Get legal advice as to how to make what you want (ie. full custody) happen.