Here's a sample database I put together to illustrate a solution that might work for you:
It was easier to do this than to try and explain it in words! Anyway, the sample database uses a join table to relate Properties to Contacts, and portals to display the related records. Have a close look at the Relationship graph to see how the relationships are set up.
I hope this gives you some ideas for your own database.
Thanks Nick. That works like a charm. I appreciate your help.