if Sets wants to try and stop her it'd actually be pretty easy! Oona will whine that she's just having fun!! and say that it's a good thing people get to see their dead lvoed ones, but will concede that humans are weak and will probably drown bc they're Dumb so she'll stop

you know, if she buys oona something tasty from one of the stalls. THen she'd want to poke and prod at her to figure out why she cares about helping out people/the humans/etc. etc. SHE WANTS TO KNOW EVERYTHING SHE'S NOSEY

so that might work out best?? /thinking face