Ah I have just created an account on family search, I see that some of the records have images now, I literally hadnt used it for about 20 years when it was just transcriptions
So it might be, that Frederick and Selina divorced and she went and changed her name to Helen. she then married Donald Beck.
Meanwhile Doris stayed living with her father but then later married a Don Laurent, but used Beck as her maiden name instead of Cocroft?
They had one son Don Laurent, who has since died but leaves 2 living children.
How would I access the marriages to check this out, do american marriage records have the father's names on them or the mothers names of the bride and grooms?