While 9 is far from a perfect card realistically the only combos that improve are 99 and super unlikely 97s. That's why I'd just fire away since you can't really get away if one of them has a set but you do want to get max value from lower overpairs. Also, I doubt you'll see many bluffs on the river if you check back since the pot is multiway so it's best to manage the pot yourself.

Being in position makes this a much simpler value bet. Over pairs won't be folding for a second barrel, and if you get jammed on then you can probably make a tight fold with bluffs being so unlikely. River is otherwise an easy check behind after you bet twice into two other regs.