Re: dojo head bans students from training with another teacher (ex student)
This is a story that I've not only heard many times, but been a part of myself.
It might be hard but you'll have to make a choice. It is a teachers prerogative to say what is and is not allowed in his dojo. And if he says you cannot train somewhere else and with him, that's just the way it is.
If you want to badly train with the other fellow, do it, and if your current teacher kicks you out, then so be it. However if enough of you want to train with the other fellow, I'm sure the teacher will change his policy.
But don't be cowardly about it, you should all get together and ask to talk to your sensei as a group. Either he will listen to you or not, but there should be no anonymity to it, that's not the martial way.