Contact Roles from multiple Accounts

Contact Roles from multiple Accounts

In more complex sales situations there may be Contact Roles with Potentials that come from more than one Account. 

For example we may be working with an outsourcing partner. In that case we need to assign Contact Roles to Potentials from both the end user Account and from the outsourcing company Account.

I tried to establish relationships by using Member Accounts and Parent Accounts, but this did not expand the available Contacts to multiple accounts when in the Contact Roles.

Is there another way to achieve this. Thanks