Part configuration in assembly

944006.SLDPRT is a design table part for 1.5" x 1.5" square tube, with configurations for lengths from 1/16" to 60" in 1/16" increments. DT-1000.SLDASM is an assembly consisting of one instance of 944006.SLDPRT. (FWIW, this is more or less the approach we use at my job to get lengths of tube, rod, flat bar, etc., in assemblies, but we use Autodesk Inventor.)

I was hoping for two things to happen:

1) When I inserted 944006.SLDPRT into DT-1000.SLDASM, I wanted to be prompted as to which configuration (i.e., which length) I wanted.

2) I wanted to be able to switch to a different configuration of the part once it was in the assembly. In other words, change the length of a given piece of tube as needed.

So, how do I get these things to happen? Thank you.

SolidworksParts And Features