odoo 9.0

The setup:

I have two records in res.partner C and E. For context C is a company and E is an employee.

Record C has a many2many relation to record E called x_employee_ids. E reciprocates this relation with x_company_ids.

I have a functionality which allows me to archive record C and have E archived along with it automatically (if and only if no other relations to E exist elsewhere in res.partner). This works by checking C's field x_employee_ids and archiving what is found there.

What I want to achieve:

I want to make it possible to do the opposite. If I unarchive C I want E to also be unarchived.

The problem:

When E is archived it doesn't show up when checking the field x_employee_ids in C. So even when I unarchive C I can't see the relationship. I would assume that the relationship is deleted but I have demonstrated that it is not.

Knowing who E is during testing, I can unarchive E myself. When I do this it reappears in the x_employee_ids field of C. So this means that Odoo stores the relationship somewhere. But where? If I know where I can make my unarchive functionality work.