You can run DCS and TMCC/Legacy at the same time, but conventional will be problematic. You can certainly run conventional on the same tracks when you're not running the command stuff, that's not a problem.
Some will say you can run conventional and command together. Trust me, it won't be a pleasant experience, they really don't play that well together. Lowering the voltage and/or interrupting the track power for direction changes will drive the command stuff crazy.