Playing with others

[Mono]

As a newbie, may I enquire if a 2-row B/C diatonic box can be played in different keys to accompany singers or this only possible if chromatic?

 

[Pipemajor]

A B/C diatonic can play in any key (with difficulty), but only on the right hand.
Depending on how many/what chords you have will determine what keys you can accompany someone with

 

[Mono]

Thanks Pipemajor, I'd be quite happy to forget the base if I could manage to handle the other side!

 

[OuijaBoard]

On a B/C, you can readily play in C, D, E, F, G, A, and B. Plus their relative minors. On a few of those keys you'd be playing a lot on the pull and working your air button. But they're still easily played.

The other keys--technically you can play in them. But it's awkward and not optimal.