"Umm aside" not-aside, I'm sorry for triggering you. it's too late for me to edit my comment and take that out but I would if I could. So this may not be obvious to you, but what's obvious to someone isn't necessarily obvious to other people, and vice versa. In any case, I can see why creating a separate account if you only have toddlers seems too onerous. Don't worry though, they'll become teenagers who want (and deserve) the autonomy and agency of having their own account before you know it, even if sharing your photos to their idevice wasn't enough to motivate you. Separate accounts seems the most reasonably way do implement a shared but-not-system to preserve privacy, a favorite reason Apple cites as their reason for doing things. I'm not sure how else Apple could do a shared system for teens.

I think there's a hack involving getting a cheap phone number for each toddler, adding that to iCloud, then disabling message delivery to that number but I haven't tested it.