Can my wife petition the US court to be the custodian or guardian to our minor grandchild's minor's trust account?

My stepson, who was a permanent resident, passed away and left some money in his trust. We found out he fathered a child in the Philippines who is now turning 4 years old. We were able to establish paternity thru DNA testing. Because the minor child is a Filipino citizen and is in the Philippines, can my wife petition the US court to establish her as the custodian or guardian to the minor's trust account we will set-up for our grandchild before we start the distribution? Honestly, we need to prevent the child's biological mother to be the guardian of the minor's trust because we were told and been proven to us that the child's mother is again living with another man (her 3rd) and has two kids with this man while still married and with three kids to her first husband who is here in US. This woman had an affair with my late son for a few months. She is unemployed and relying solely on child support. Her whole family, mother and sisters, has a reputation of having low moral values.