Unique groupings

Gurus,

some background

report comes in with

Sales Doc #, line items, qty

I have created groups of line items so they appear in larger buckets..  ie items 123-125 = Group A, 234, 356, 765= GroupB

this is fine.

Now I need to look within each sales doc and assign another grouping ID based on whether Doc has GroupA  or Group A+B or GroupB, each with new group names so these docs can be filtered/separated etc.  ie.  System C = if GroupA and GroupB foreach sales doc  System D= If only groupB foreach sales doc.

I cannot figure out how to do this in Webi.

Ideas?   (i know there are some)

oh..and its BW...so no Universe to work with.

thanks

jim