Since the supplementing settings are inactive for proximity breaklines then I'll have to say you cannot apply supplements to proximity breaklines. However when you first add the proximity breaklines you will see an option to convert them to standard breaklines. So what I think you can do is use the option to convert the proximity breaklines and after they have been added to the surface, import them back into your drawing from the surface. This will generate them as 3D featurelines. You can then add those as standard breaklines using the suplement options. It's clunky but I am not aware of any more direct approach.
I've little experience with Survey figures but is there not a way to add them to a surface directly from the survey database?
Neil Wilson (a.k.a. neilw) Infrastructure Suite/C3D 2013, LDT 2004, Power Civil v8i SS1 WIN 7 64 PRO HP Pavillion h8xt, i7 2600, 12 GB RADEON 6450, 1 GB http://www.sec-landmgt.com
Survey FIgures you can add them directly, but cleanup and editing is a nightmare. It's much easier working with straight up Plines. I've found that since we use some of these breaklines along the way for the odd alignment creation that getting the figures converted to a flattened Pline helps me down the road. The autogenerated survey figures based on figure prefix databases is the way to go. In fact we usually sort our CSV file from N-S or E-W and the breakliens are virtually created without alot of editing. Editing survey figures (within the survey database) is very cumbersome none-the-less. Thanks for the idea though I'll give this a try.