Jean,
Several thoughts come to mind.
First, you use the word "forced" which leads me to believe you are really uncomfortable with switching roles from single to multi. This may be a good indicator that you need to give this more thought.
I assume you would have to give up all your current clients to do his work. If you decide to do this, please refer these clients to other VAs so they don't feel like you walked out on them. Also, you'll need to be honest with them as to why you can no longer do work for them.
Can you do his work on a part time basis?
Lastly, has he given you an outline of what he expects, how much time each project will take, etc. And, is we willing to sign a contract in advance?
I'm sure other VAs will pipe in also. Please keep us all posted.
Carol
CJ's Virtual Business Solutions