MIL having play dates while watching my child

Musashi

My son is just shy of a year old. I am a SAHM and normally have him by my side 99% of the time, but I wanted to have a day to get everything in order for tax season so I asked my in-laws to watch my son for the morning and afternoon. They agreed and when I went to pick him up my MIL mention my SIL came over with her two children and they were playing with my son. I assumed SIL stopped in for something, but my mother-in-law said she called her and invited her and the kids to lunch so the kids could play with my child.

Now had I known about this plan I would be ok with it, but I am not thrilled this was scheduled without me knowing (she could have also texted me this plan). While it is her house, she was watching my child and I was under the impression he would have their full attention. In my opinion if you offer to watch someone’s kid you should let the parent be aware of any plans that involve other people within reason.

I am being unreasonable feeling miffed about these turn of events? For the record she texted some pictures during the time the cousins were over but never mentioned, nor included them

in the photos.