you need both of the parents to agree to have their child's last name changed
You indicate they have "Contact", but what is the status of Custody? If the Father has visitation, partial or shared custody, legal& or physical....No, you cannot change the Surname of the child without the Fathers explicit consent!!
Legally, probably not. Not unless they have legal custody of the minor's child.
yes
See Related Link
It could be, if you don't have custody of the child.
If you are under the age of 18, then the consent of the CUSTODIAL parent or Guardian is necessary. So, if this parent does not have custody, then they cannot sign for you to get married.
Yes.
Generally no. A change in custody must be made by a court order.
Yes she can.
their parents
Child's Choice of Managing Conservator (custodial or primary residential parent)If the child is 10 years of age or older, the child may, by writing filed with the court, choose the managing conservator, subject to the approval of the court. TEX.FAM.CODE ANN. § 153.008. The court retains discretion to determine whether to honor the child's choice. Further, in a non-jury trial the court may interview the child in chambers to determine the child's wishes as to conservatorship. TEX.FAM.CODE ANN. § 153.009. Upon the request of a party, the court must interview the child.This is up to the judge. The Texas law does not specifically address this. But, there are alternatives. see links
Yes. The minor parents have the same rights over their child as adult parents do. The grandparents have no legal right to the grandchild.