I am trying to make a truss that has a different length bottom chord from the top chord. I put reference planes in the family lock the bottom chord to these reference planes, and import the truss into the project. When I initially place the truss everything looks fine, but if I make any adjustments to the properties of the truss the bottom chord will extend to the length of the truss. Attached is a couple of pictures of a Warren truss that comes with Revit. In that family the bottom chord is shorter than the top, similar to what I want. When I initially place the Warren truss everything looks fine (see attached), but if I change the height the same thing happens in that the bottom chord defaults back to the truss length (see attached). Anybody else experienced this?