Update query

[Blkblts]

I appologize in advance for this confusing question.
I have a table that list parentID,Desc,ChildID,Desc

Here is my problem...
The hiarchy of the system I extracted from is you have a group (parentid)which is a "parent" to a subscriber (the childid). The subscriber(parentId) which is a "parent" to the members (childId)in a family. The problem is a subscriber can be a parentid and a childid.
The parentid could be 50901 and the child would be 50902. But I can also have a parent id of 50901 and the member is 50901.
Ultimately what I am trying to get is the Group number to the members, but Group is not a direct "parent" to members you have a subscriber in between.. Any suggestions?

Thanks
kim