Project Navigator | Unit Conversion

[kuripitomi]

I hope someone can shed some light...

I am still pretty new to using the Project Navigator in AutoCAD MEP 2015, so I've done quite a bit of searching on the net prior to posting my question here...
After creating a new Electrical "Construct" I scrolled over to the architectural "Elements" and "Xref Overlay" the appropriate floor. My drawing area now shows the correct architectural plan. I then scrolled over to my RCP construct for the corresponding level and "Xref Overlay" it as well. Once the construct comes in, I see that the scale of the Architectural construct and the RCP are different.

When I select the architectural xref and check its properties I see that under "Misc" → "Block Unit" = Feet → "Unit Factor" = 1'-0"
When I select the RCP xref and check its properties I see that under "Misc" → "Block Unit" = Inches → "Unit Factor" = 1"

I've tried selecting the architectural xref and selecting the calculator adjacent to the "Unit Factor" value, but the "Apply" button is greyed out. I assume that's because it's an Xref and not a block, but I'm not sure.

Is there a way to Xref my architectural plans through the Project Navigator so they scale according to the units which I already have set? Or do I have to go about scaling the xref in a different manner?
If it can't be done through the project navigator, will I have to continue scaling the xref every time I receive and updated file?

Hope this makes sense and thank you in advance. Your feedback is greatly appreciated.

[Coloradomrg]

All you should have to do, is go into your architectural construct and change the units to inches instead of feet.