It's me from the other thread
Actually I gave another solution before that one which in the Header would offer combo boxes for Contact and/or Property selection. Then, based on the selection, it would populate the subform in the Detail section.
What are the additional "subforms" that you would want to add to the PropertiesFrm???? Would they not be on the ContactsFrm if you had one?
I think you need to break up the functionality:
1. Form for adding adding Properties by Contact, Combo Box in the Header for selecting Contact to add properties to.
2. Form for adding Contacts By Property, Combo Box in the Header for selecting Property to add Contacts to.
1 & 2 would both utilitize the three tables you mentioned.
3. Form for editing the Details of a Specific Property, Combo Box in the Header for selecting the Property.
4. Form for editing the Details of a Specific Contact, Combo Box in the Header for selecting the Contact.
Forms 3 & 4 could have buttons to open the applicable Form in 1 & 2 above.
Something to remember... The more complicated a form is, the more frustrated your user(s) will be!
If this database will be used by others, have they been queried with ideas about the User Interface? The User Interface is what makes it Good or Bad for the User. A User Interface built just by the Programmer/Developer will likely be poorly received.
I noted in your profile "Student". Are you a student, and is this a class project?