I wholeheartedly recommend Bubblemakers/DSD for this age group. We just had a gathering of "8 year olds and up who happened to know each other through Cub Scouts"

at our local Sport Chalet under the full auspices of the PADI and Sport Chalet-endorsed and -insured program. They had a blast! 8 YOA is minimum for Bubblemakers. A couple of things that made our group of 7 kids go very smoothly:
1) We recruited a class of recent DM graduates and soon-to-be graduating DMs overseen by an instructor. We had almost a 1:1 ratio, adult to kid. The DMs had as much fun as the kids.
2) Go slow. The big concerns for this group are basic swimming, mask flooding, and most importantly, equalization. Again, go slow, and build up to it.
3) Parents stayed the whole time, sitting on the pool deck. At first, I think their motive was understandably protective, but then they saw how much fun the kids were having and it was a real eye-opener of a fun new thing Mom and/or Dad can do with their kids. Be up front with them telling them everything to expect and discuss it before hand to get their buyin and get their questions answered.
4) "Toypedos" were a big hit. Something to do while underwater and everykid likes to play catch. This is just the underwater version...and it helps to relax them to boot.
Have fun, good luck, and go for it! PM me if you have any further q's.
Cheers!