I use KCD to draw and Cabinet Parts Pro to produce my cabinet parts. What I have found is that I very rarely (almost never) have to draw special cabinet part pieces. When I need to, I just draw it in Vcarve and and toopath it. It is so rare that I don't even save the files.
Two ideas that may help answer your question. One, if the parts you are talking about are 'standard' parts for a cabinet that need modified, you may want to batch import dxf files from KCD to Vcarve, nest them, make your modifications to the particular part and then toolpath using a combination of toolpath templating and vector selection by layer. The benefit to this is you get to nest your special or modified part with all the others instead of on a separate sheet. It's a little complicated, but once you learn it and get it down, its not too bad. Two, you draw the parts in their own files with layer names for the different processes that are common amongst the files,and save them to a special library or folder. When it comes time to gather and nest all the special parts for a job, open vcarve and set up a file for that job, open another window of vcarve (so you can have two different files open at the same time) and use the second window to open the individual files you need to copy, select and copy the part in the second window, then switch to the first and paste. Go back to the second window, open your next special file ,select, copy, switch to first window, paste, etc. When you get all the parts you need, again, nest and toolpath with a combination of layer selection and toolpath templates.
I'm not going to take the time to look up and link the relevant tutorials, but if you look for the ones that cover layer control and toolpath templates, and watch them, they will give you more details on those topics.
There may be an easier way, I don't know. If someone has a better method, chime in. I would be happy to learn about it as well. This is how I deal with the question you asked about.
Hope this helps,