What a sad and horrible story. If the father did marry BO’s mother, it apparently was a bigamous marriage.
Barry's father, a Muslim, was already married. That was legal in Kenya, where the Brits agreed to allow Muslims to follow sharia law in return for an agreement to rule the place from the Sultan of Zanzibar, who had previously claimed the coastal province.
So we have a conundrum. If they were married in Hawaii, then the marriage was invalid. If they were married as Muslims in Kenya, then it was valid. I believe under Islamic law and custom Stanley Ann would have had to agree to become a Muslim, and of course Barry would be considered Muslim from birth.
Possibly they were married twice, in America and Kenya. Stanley claimed surprise at finding out that her husband was already married, but who knows?
Or, possibly, they were never married at all. We don't have any marriage certificate. And as some have pointed out, Stanley might have gotten the divorce decree even if unmarried, to clarify her custody of Barry.