More of a WWYD. Let's start by being clear that everyone is lovely and I get along well with all of them.
We had people here at the weekend and there are two crawling babies; ours and BIL/SILs. I've just found a pill on the floor next to the playmat for the babies; nobody told either of us that they had dropped a pill. The only people with pills they take in the day are MIL and AIL.
If it was AIL, then she sees the babies rarely and it's better to say nothing because she just got back on good terms with PIL, who would both be angry if they thought AIL wasn't taking enough care around the babies.
Given the seat the pill was next to, it was more likely MIL however, who does see the babies a lot. DH thinks she must have not realised or would have told us, but she carries daily pills so I don't see how she wouldn't have noticed. She has the babies visit at her house, she might get them on her own at some points and she's around them an awful lot; so I feel like it would be useful to remind her to be super careful with the pills. However nicely I put it, I know it'll upset her that she'll know she's done something very wrong, and as above if it actually isn't her pill then unfortunately it's likely to cause big issues with AIL. But I'm not happy that there was a pill on the floor where my baby plays and nobody gave me a chance to look for it.
As a side point, should I tell SIL so she can remember to be careful with the baby on their floor? That could cause issues with her taking their baby round less and if I was telling MIL I think is unnecessary.
So, who would you tell (if anyone)?