Barry And I have been back & forth over this very issue for years. Yes he 's correct,, you may get away adding a engine with a few other engine on the track but.... This is probably what might happen....
Engine not found
engine adds with no name
Engine adds but borrows the name of a previously added engine
Engine add a previous engine that has already been added
Two brand new engine with the same ID might give you a hard time adding unless using a programming track one engine at a time.
Man! Save yourself a head ache and use a programming track or equivalent...
Our layout is big . 4 tiu in super with an excellent dcs signal. We wouldn't dream of adding without a programming track.
On the other hand
If you have 3 or 4 engines try it it. you can always delete them and start over.
I get a kick out of some who say "I don't take any engine off the track and have over 50 engines"
What they don't tell you is ..They're sitting on dead tracks.