Is it possible to combine relate fields to have all related results in one dropdown?

Sugar 9.0 Professional OnDemand

Been banging my head against the wall on this issue, so hopefully someone here can help point me in the right direction.

Our process:

Leads --> Prospects (Opportunities) --> Current Accounts

Our leads our provided by the marketing department and are not assigned to any user. When a user wants to begin the sales cycle with a lead, they claim(convert) it to a Prospect (Opportunity). From there, as the sales staff takes the prospect through the sales stages, once it equals 'Closed Won' a logic hook creates a 'Current Account' record.

Our Contacts module holds contacts for both Current Accounts and Prospect Accounts (Opportunities). We would like to relate these contacts to their respective account/prospect record and I think the best way of doing this would be to create two Relate Fields in the Contacts Module.

My question to you is, is there a better way? If not, is there a way to combine records from two Relate Fields(accounts and prospects) into one, so when the user wants to link the contact to a current account/prospect record, records from each of those modules are able to be searched and selected from a single Relate field?

Please let me know if I can clarify something.

Thanks in advance.