I just wrote the following mitzvah note for my daughter:
"Dear Morot,
Hodayah is such a great big sister and such a good helper. Her brother wanted to play with blocks with mommy, but mommy had to go to the bathroom. Hodayah took the blocks and took her brother to the playroom so mommy was able to go to the bathroom. Thank you so much, Hodayah!
💜 Hodayah's mommy"
(She actually said to Hillelly "Come baby brother. You want to play? Big sister will play with you. Come!". It was sooooo sweet and I almost stayed to watch rather than go to the bathroom.)
P.s. a year later, I never actually sent that note bc I had so many other good ones that week, b"h, and I saved it for when I would have a lull, and then it was too far from the event that o thought Hodayah would be confused so I never ended up sending it. Oh well.