I am working on a special truss with 4 different diag steel member sizes, but typical revit truss family only allow to specify all of the veritcal members to be same size, and all of diag member to be same size. It's possible to size the vertical members to different size?
Currently, there is no such function to set different framing family type for the member of the same type in truss family editor. You have to change the framing type used in the member in project one by one. (select the chord and unpin it, then change its framing type)
The function you mentioned might be achieved by Revit API work. If you want to know more about API, you can check the API dicussion group here: