My sister lives in Kansas and she had her son two months ago and my mother is taking care of him. My sister wants to sign over her parental rights and give custody to my mother without having to go to court. What forms do they have to obtain for this to happen?

You can NOT do this without going to court.

Sorry.

You ALSO can not do this without the baby's father's permission.

Yes, no way to do it without going to court, only they can change custody . Also without the fathers permission it can not happen either.

Even guardianship will require the court to approve