Based on recent post I made:

"And second question - could it be somehow possible to choose by default
all groups recipient is already member with and leave selections which User
is not member unchecked?"

I thought this through - and I am trying currently to achieve following

I have two picklists
-Groups User is member (greyed out in gui)
-Groups User is not member (Users has possiblity to choose groups he need)

I have difficulties to make query for querying if recipient is not or is
member of group...
based on query towards group entity - Members contain %getMember%

If I remove member contains /not contains clause from queries - they work
like a Buick...

Does any one have worked with displaying groups recipient is member / is not