To be honest I can't make heads or tails out of your scenario (...probably my fault) but a couple of points on the general subject of 'How to refer to a field (not a control) in a subform and vis-à-vis Unbound Controls on Continuous View Forms:'
If the Field is part of the RecordSet of the Form/Subform, but doesn't reside on the Form/Subform, itself, you can, in VBA code, still reference it. If the Field name is, for instance, FIUT (Field In Underlying Table), you'd simply use
Me.FIUT
like you would for a Control.
Actually, an Unbound Control (one not Bound to a Field in the underlying Table/Query) can be Record-specific, in a Continuous Form...but you have to use an Expression in its Control Source. In the Control Source, you'd use this:
=[FIUT]
This Unbound Control will be Read-Only, as all Controls whose Control Sources are based on Expressions, but they will be Record-specific!
The usual way of displaying data from a Table/Query not part of the Form's RecordSet is to use the DLookup function, once again in an Expression in its Control Source.
Not sure if that will work for you (as I said, I'm fuzzy on your goal, here) but you could use, in this case/example, FIUT in the Where Clause of the DLookUp.
Linq ;0)>