You cant do it, you need seperate groups. I am sure once Paul reads this he will give the same advice. It is different skills you are teaching. The basics will bore an advanced player.

You also have the ask the question of do they want to learn new skill or just play about. You will probably find more advanced players just want to play being told the odd piece of info rather than having a dedicated proper training session. 

If you do want to go down this route with your club, show them small things at a time and then let them play to have fun.

I only ever had 1 club of complete novices ask me to coach the club for one night as they were wanting to enter our league and they wanted me to show them tactics such as where to stand in doubles and mixed and when to go sides and front/back. I have to admit I did enjoy it. A few of them became decent lower league players