@Kite1
I am so saddened by your experience you report here, and what I say next is said with absolute sympathy.
Looking up legal terms on the internet is only going to cause you pain and confusion. It will not help you understand your story.
I think you are perhaps mixing up UK and USA legal terms with sociology metaphors. I’ve already tried to give you a comprehensive explanation of what legal fiction means, strawman arguments are a totally different thing, and are generally not a true legal term. It is a term you would use when critiquing someone’s argument by interpreting it in bad faith. An example of a strawman argument:
Me: I adopted my children to create a family where they are safe.
Them: So your saying their birth parents are evil? That’s wrong!
It is a strawman argument because the other person has created a ‘straw man’ (an extreme misinterpretation of my argument) and then ‘knocked it down’, thus ‘winning’ the argument.
I am quite confused by your use of the cestui que vie act (I guess you mean 1666?) and I’m not going to go into it because what your referring to is mainly US law now and is mainly used in complex land ownership disputes.
If you believe you should not have been removed from the care of your birth family, then you must be in so much pain and I am so sorry. Please, do seek out help through the NHS pathways or other groups of adopters.