Just conjucture about why the divorce when no marriage. If she had put SR on the BC thinking they were legally married, then she would probably have to show she had custody in order to leave the country and legally live in Indonesia with Lolo. Remember the rules in Indonesia about children of certain age living in your home. They had to be yours...thus the adoption (of sorts)
Not having custody is NOT giving up your right to the child. It could be that SR signed documents relinquishing parental rights. He gave up custody whether he was present at the divorce or not. Did he give up parental rights in 71? If so documents should be filed in HI family court division.
Giving up full parental rights so an adoption can go through doesn’t need the parent to be there in person for several weeks. All it takes is a signed and witnessed statement presented by an attorney and that’s in today’s courts. I can’t see a judge in easy going HI back in ‘71 making a resident of Kenya, who had never been part of the child’s life, hop a plane just to transfer the kid over to the grandparents. Even less so if it was just custody. And if Lolo had adopted him then why wasn’t Lolo the one having to physically be in HI? While I believe Sr.’s happy little family Christmas visit involved custody of the little prince, I’m suspicious that there was more to it than that.