There are many ways to do this but nothing automatic. You can create a part in your assembly that is the simplified beam model of the master CAD. You would tie that model to points on the master CAD such that the idealized beams change in length according to the master. Then you would make a simplified representation with any parts that do not need to be modelled excluded from the rep. (the ones simplified by beams) However getting the beam cross sectional properties to synchronize could be difficult as there is no direct way.
Another way is to have each beam part contain both their idealized model and their 3D CAD and suppress the 3D CAD before going into simulate. I have not done family tables in many years but I think you might be able to have parts substitute on demand with that as well.
It all depends on your focus. If this is a one time project then just make a separate model that represents what you want. If you are doing these types of structures often with many variants then you would want to find ways to streamline the process and Creo has a significant arsenal of tools to assist in that like: mapkeys, process guides, parameters and relations, Pro/Program, API toolkits.
I do not personally do framework designs but this article seems relevant to a tie between Advanced Framework and simulated beams as well as simplified reps to replace solid models with simplified simulation ones. If you use this or run across an example or YouTube or something of this technique please share with the community.
https://support.ptc.com/help/creo/creo_pma/r10.0/usascii/index.html#page/advanced_framework/Creating_Beam_Structure_Models_for_Creo_Parametrics_Mechanica.html#
