Be sure you are not confusing the DCS Commander with the DCS Remote Commander.
The DCS Remote Commander can only run 1 engine. The DCS Commander can store up to 10 engines however, it has limited power (something like 100 watts/6 amps) so while it should work as you will seem to use it, please remember you most likely will not be able to run too many more engines at the same time. Also, it puts out DC to the track so if you want to run any AC powered engines on the same track you won't be able to.
-Greg