They should be ok. Most of my hand raised over the years ate 4 kinds of milkweed leaves depending on what was available and seemed not to mind switching around. Tried to keep on same kind til after 3rd instar at which point they seemed to eat anything as in Very Hungry caterpillar!
I can't tell how big yours are...
Suggestion: To see if they will switch
Get a plastic container (tupperware type) with lid
Pick one or two fairly young and tender common milkweed leaves (rinse well)
Put in container along with cats and a leaf each of your seedling plants (half eaten ones ok)
Bring inside and watch which gets eaten...
I like to put the leaf they are on on top of or leaning on the leaf I want them to go to next...
Good luck
I found it easier to raise them inside
https://monarchbutterflygarden...
