So you want to make a bunch of small parts at once in one setup, and using one vise. Make a strip of parts in a set of big soft jaws:
The parts keep a strip underneath. To finish, flip the whole thing, drop it into softjaws of appropriate “negative image” of the parts, and mill of the back.
An alternative would be to make a tooling plate that goes in the vise and acts as a pallet. Use Mitee-Bite clamps or the equivalent to hold the parts. Make at least two plates so you can load one while the machine is working on the other.
If you start getting some chatter, the backing is probably too thin, or your jaws are holding it well enough. You call also try some big “Jaws of Doom” like I made up for 2 vises:
The “Jaws of Doom” have been handy to have from time to time!