Facebook might not be giving up on Group Stories just because it's cutting them from its main app. App sleuther Jane Manchun Wong has found test code for a Group Story feature in Instagram. There's no mystery to how it works -- you'd just choose to "share to Group Story." Still, it could be helpful for those moments when you'd like to recap your adventures for a smaller social circle beyond those you've marked as Close Friends.
Like other tests, there's no guarantee this will make the cut. That's particularly relevant given the fate of the equivalent feature in Facebook. However, it might stand a better chance of survival in Instagram. Simply put, Stories are more of a staple here than they are in Facebook -- it makes more sense to include them in this app. It helps that Instagram already has Story stickers that directly link to group chats.