I have a control valve assembly that includes a bracket for mounting the control valve to an external part (unistrut channel).  Based on different assemblies that I will be putting this into, the vertical position of the bracket will vary (valve may be a variable height above the unistrut based on particular piping set up).

I would like to keep the bracket in the control valve assembly for ease of use.  When I insert it into a larger assembly, I would like to mate the bottom of the bracket to unistrut which will finally set the height of the bracket relative to the control valve.  In the control valve assembly the mounting bracket vertical position is not set.

However, Solidworks does not allow me to mate the bottom of the bracket to an external component because that would alter the bracket location within assembly.

Is there a way to do this.  I hope I have explained this well.  Included is an assembly.  The control valve flow axis is mated to a line in one sketch.  The unistrut is represented by a line in a separate sketch (2in below flow axis and perpendicular).

Marty