See my attached drawing. I'm trying to control the width of the drawer with the flush Mate in P2( for part 2), and the length with the 16" dim on P1. When changing the value of flush Mate, P1 and P3 are joined, but not P2. P3 was created from projected geometry from P1 to P2. This situation even stumped my Inventor teacher. Unfortunately, I don't think older version users can open my file. I can send a PDF or a screen print if needed.
In my experience I cannot imagine a way to upload an assembly on its own without the parts and to expecting from others to download and open this assembly...
You need to upload a .rar file with everything (parts & assembly) included.
Then more than happy to help you to sort out anything around parametric models!!!
You need to use what is called an adaptive part.
Within the model of the drawer, mark the extrusion dimension used to create the width as adaptive.
Within the assembly mate both sides of the drawer to the geometry which is intended to control it. Mark the part as adaptive.
When the external geometry is changed the drawer width should now update.