I have several parts that are dimensioned completely using reference geometry. I want dimensions to be chosen automatically that make my assembly constraints valid. I.e., If the left most plane of a part is constrained to a particular plane on another part, and the right most is constrained to another plane on another part, I want the part to resize itself to make those constraints valid.
okay it is easy. go tools--> options-->infrastructure-->part ifinfrastructure
Go general tab and select "keep link with selected object"
After that every external reference will link the other part.