You may find it useful to encourage students to do some of the work for you...
If they post an item to Seesaw that features another student, they can edit the post and tag other students in it, so that one post will appear in the other students LJs (if you approve it).
Any caption will be shared across all the students, but they can either edit the item to add to the caption, or, preferably, add a comment to possibly clarify the relevance of the post to them.
Scenarios where this can be useful: