I have what is basically an A-frame with crossmembers. It is
modeled using Weldments in a part file. When the length of the
a-frame changes some of the cross members and trims need to be
suppressed via a design table in an assembly. I am controling the
length the a-frame in the assembly via a distance mate. Is it
possible to suppress the crossmembers via the design table in the
assembly?
In the weldment part file add a sketch with with a driven reference dimension. Add this dimension to a column in the part's design table, in another column "E" and an additional column for the suppression state $STATE@Bodyorfeature1 of what ever the body or feature is you want to suppress and in this column enter the formula =if(E4>2,"U","S") or other <>= criteria you want
I am not sure this will update properly without going to the design table when you make changes.
Another suggestion, make a bunch of configurations in the weldment part how you want them configured and then use the design table in the assembly to pick the part configuration you want to use.
You may want to dig into Layout Sketches and In Context Assemblies to complete this project.