I think it depends on the temperament and size of the O and JD..I have a 4" butterfly with a 2" ebjd and they are doing fine.
My butterfly has never tried to jump out..and despite the many claims of them being delicate I have yet to see that from him.
I guess if your O and JD are small just give the butterfly lots of hiding places and floating plants to hide in and give it a try.
But I think when your O gets full grown the butterfly will become food.
I like the idea of putting the butterfly in the 30...maybe get a few!