Misplayed PLO8b hand?

[querulous]

Played on FT, so recreated from their crappy hand history, sorry.

Literally my first hand at the table, blinds are $1/2, I have $200 behind and have both players covered.

I'm in BB, MP player limps and SB completes. I check with As 3s 6s 9s. Pot is $6.

Flop is Ad 2s 8c. SB checks, I check, MP checks.

Turn is 7s. SB bets $4, I call $4, MP min raises to $8. SB calls, I call. Pot is $30.

River is Tc. SB bets $10. I call $10, MP goes all in for $17.25 more. SB and I both call.

My thinking at the time was that SB and MP both made 87x2A for low on the turn and that I didn't want either of them folding. I wasn't sure how many of my outs were actually live either. Should I have put in a third raise on the turn? Or would you have folded to the $4?