moh also as "flower girl" ? ?

If you and the MOH are both down for this, then go for it!

Also, tossing petals isn’t a requirement. Or they can be sprinkled/set in a design in the isle before the ceremony.

A flower girl or any type of replacement is never required. Have you asked if she wants to do that? She wouldn’t carry her own bouquet in that case. Often if there are petals and no flower/ring children, the florist places the petals.

That’s what my sister (MOH) did! She thought it would be fun and was happy to play that role. The bridesmaid next to her carried double bouquets and handed my sister’s bouquet to her after she set the basket down.

As long as she's OK with it, I don't see a problem. Also the florist could line the aisle with petals beforehand.

Thank you all for your replies.
My MOH suggested this idea.She will not have a boquet. Instead she will be carrying a parasol and wear a wrist corsage. I am thinking perhaps a pouch like purse that will drape on her wrist to hold the petals.