Strange Problem with a relationship and record picker.

I have a long standing table, Core Returns, that has a lot (too much, but just blame Admins long retired) of information.  There is a field that gets filled in at a point well after the record is created, automatically, through updates.  That part is working fine.  I recently added another table, HVNE PO's, as part of a different project that does share some data with the older table.  There is a reference to an 'Equipment' number.  That number is the Primary key in the HVNE PO's table.  I have it set where the HVNE PO's table is the parent table and Core Returns is the child table as that same equipment number can and does crop up in the Core Returns table multiple times.  The Equipment number, however, does not necessarily exist in both places.  

The Goal is to allow a User to look from the Core Returns table and see if that Equipment number exists over in the HVNE PO's table.  The users' decision about what to do next is impacted by this.  So that's what I want.

My Relationship is like this: HVNE PO's is Parent, Core Returns is Child.  Equipment is the Text (Key Field) in HVNE PO's.  Ret_Equipment is the Text (Reference).  The reports display everything as expected. Now, in the form to look at records in the Core Return, when just looking, it displays as expected, but when you go to Edit the record, Ret_Equipment displays a date and gives a drop down with completely unrelated information.  If I don't touch that field, make other changes that I need to make, when I return to the report or the eyeball view, it's fine.  The problem is that I may occasionally need to edit that field and now it's all screwed up for that workflow.

I have a gut feeling that it is a simple setting somewhere, but for the life of me I can't find it.