Hi,
you can try this method,
once you complete mirroring the parts or a subassembly,
Creat new product in the main assembly and copy all the symmetry parts into it, and delete the mirrored one. This will loose the positional link with the original parts but it will have the geometrical link. And...
Hi,
go in Tools/Options/Mechanical/Part Design...
And look for the General- External References,
check -keep link with selected object.
This means it will create a group with externally
referenced objects.
this should work.
cheers
Rav