Mates relations are lost in animation ?

Hi dear Friends,
I am not a professional but attending some courses for Solidworks and getting my experience in such a way. Therefore I have a question regarding animations by SOLIDWORKS. I am sure, you could help me.

I have created an assembly like a human body (see picture attached) where legs and hands are fixed (coincident) to lines (grey) of the main body.

Problem description:

After floating (unfixing) the main body the legs and hands still remain attached

BUT

after rotating the main body the hands and legs are getting separated from the main body, although the legs and the hands were mated as coincident to points of the main body. I do not understand the reason. Please help me.

Than another question, why the "fix" function is absent if I add this assembly into another assembly project ?

Thank you in advance.

Tadeus