Many to many relation in Parents to Children tables

Many to many relation in Parents to Children tables

I read in some older posts that this may not be possible, but i wanted to see if there is a work-around.

I have two forms, one "Parents", and one "Children".
A Parent record can have multiple children, but one Child can also have multiple parents (father and mother).

So far I have setup a Main form "Parents" with a subform "Children". This seems to work only one to many since I cannot lookup existing children records in the subform, only add new records.

Does this sound familiar and is there a work around? For example to make both main forms and link those somehow, i.e. not using parent and sub form?

Thank you.