Cross-referencing Parent and Child Company Records

We have many affiliate companies as clients where each affiliate has it's own "Inventory" record, and have a Group Name field that establishes the affiliated companies and a field to identify Parent versus Child for those that are part of a group. Based on that, is there a way to populate a field (Affiliates) in the parent record with the names of all the affiliate companies associated? In the current database, they're manually updating a field to show the names of all affiliates.

Even better, can we set up a way to link from parent to affiliate records and vice versa, allowing someone to easily jump back and forth between the records, using those Group Name and Affiliates? I think I know how to do that to get to the parent from a child, but not how to get to multiple children from the parent.

------------------------------
Lessa Kennedy
------------------------------