Why not use hotlinked modules?
You only need a master layer for the module, that can function as the toggle for on and off.
Depending on how elaborate the options get, that might work well?
A little more info about how I would set that up:
Make extra stories for the different versions in the original model. Draw the optional elements here, setup a publish set of these stories to publish to module file.
Place these hotlinks in the 'real' stories. Use masterlayer named option 1, option 2 etc for the modules. You can now toggle the option on and off. Using layercombinations and layer priority, you can make sure that elements don't interact with your model, if they shouldn't.
This way you keep everything in one model and with clever use of trace and reference you can work on the optional elements in relation to the rest of the model (with exception of the 3d window, obviously).
Erwin Edel, Project Lead, Leloup Architectenwww.leloup.nl
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