If you are not satisfied with the provisional custody by mandate, you can attempt to litigate for custody. You will have to prove to the court that that parental custody will cause substantial harm to the child. That is a difficult standard to meet. If you are unsuccessful, you may find that the parents are no longer willing to extend the provisional custody they are presently voluntarily granting to you. If you do try to seek custody, given the burden of proof and the possible consequences of an unsuccessful action, it would make sense for you to work with a very good lawyer.