Thanks Jim 1
to confrim: In the course of my research we found out Mary Anne or Anne Mary had my father in law illegitimately and put up for adoption
When she met her husband they adopted him back and changed his name, so my father in law has had contact with PAC over finding out his roots - quite a shock for a 74 year old man who through his dad was his dad
Anyway PAC have not been able to find anything out about where his mum came from / or her roots , so if they can’t crack the case I wonder if I will ever solve this

The more research I have done am thinking you are right with theory 4 - and we will Unfortunately never find out the truth