Products belong to family "ABC".
to achieve this i tried creating formula field on Opportunity Product to pull the family value from Product. But i can't use formula field on rollup summary's filter condition on opporunity. so that is one dead end.
Another solution i tried is creating another text field on Opportunity Product to store family value and updated it using workflow(create&edit) with Product family value. But this workflow will not fire if Products family was updated. so thats other end.
I am out of ideas...Anyone has any other ideas?