Nick,
Terrific idea of using the Referrals table to solve your problem. That was my first thought when I saw the title of your posting. But if you're trying to run Receivables lists or Aging reports for a "parent" group, Referrals may not work. If the number of "parents" is not too large, you might want to use one of the Receivable Client user defined fields. Create a quick list of your potential Parents and require a list match. Format the quick list entries with [client number] - [client name] to make the process more convenient. The user defined field can easily be added to modifiable reports as a selection criteria.

Hi Nick,

Another suggestion that is coming soon (V20.5 Early June)- A new Custom Fields option on the Edit menu will allow you to define an unlimited number of custom fields for most Sage 100 Contractor windows. You can create custom fields for most types of records, except ledger transactions, accounts, daily payroll, and recurring transactions.
Unlike the limited user-defined fields that came with previous versions of Sage 100 Contractor, custom fields
are based on field (data) types, so that you can use custom fields in ways that were not possible with user-defined
fields available in earlier versions.

I just didn't want you to complete a lot of work, when a new feature coming very soon, may be a better choice for you.

If you have any questions, you can contact me at [email protected].