My mil would be the one to buy clothes for my eldest that are waaaayyy too small-- like she liked it so much and had to buy it but it was probably on sale so it's the wrong size. The last time she did, she demanded a photo which I took but my daughter's belly was hanging out of the sweater...pretty funny but very obviously too small.

I would have your eldest wear either of the adult pjs-- so the ones meant for you or your husband. Then whichever one of you defaults to no pj's, that person takes the photo and send her that. To me, that's says: we completed your bizarre mission.

Honestly, donate them-- a quick look up in your area and you could find a women's shelter-- they have kids and even men that are helped by these organizations. I like donating newish clothes there bc typically, those people will get first choice and then anything not chosen, the organization sells in its shop. Nothing wrong with goodwill, it's just this seems easier to make a quick impact.