Is there a "MATE" or "GROUP" function in Composer?

I have a Composer assembly open. I have imported via merge with existing document additional parts (nuts, bolts, washers, screws). Once I place these additional parts to their respective locations, I "Create an Assembly Group and drag in all the associated parts. Now when I click on this I can move the assembly and additionall parts I attached. When I click on any one part, I would assume it would act as a group and highlight all parts preventing me from dislocating any one part, but that doesn't hold true. If I want to keep a nut, bolt, and washer to stay together forever I can't seem to get them to stay together. Sometimes when I go to move the group by highlighting it, the part moves but the fasteners act like they were never picked to come along. What gives? How do I get these things to forever stay together as a group?

Thanks in advance,

gb

SolidworksComposer