We enjoyed them inside for a couple days, but once the cats figured out what was fluttering around inside the habitat, they started a stake-out to see if they could catch one. So on our 2nd to last day of school we started the day by going outside to release our little butterflies. One flew off so fast I don't even know where s/he went to. The other wasn't too far behind, and the 3rd seemed to be telling us "I got snacks; not going anywhere right now."
Our 4th, and final, butterfly is "flight impaired". Instead of symmetrical wings, the right side is a bit....off and not well-formed. Oh, he tried to fly away, but just fluttered to the ground. We rescued him and brought him back inside to live out his life. I couldn't stand the thought of him becoming a part of the food chain.
Butterfly #4 resting on Charlotte's hand
You can see his asymmetrical wings here
About a week later we went on a family bike ride and were down by the river. We stopped for a moment and there was a painted lady butterfly. We watched it a while, and it briefly came to rest on my hand. I think it was our butterfly.
