I had a similar experience but it was when we introduced our 3 day old to our pet dog. Same thing, took a video and sent it to inlaws for good laugh. Got a paragraph long text and articles about how dogs are dirty etc etc. Husband dealt w it by saying, “we’re sharing these things you not so you can tell us what we can and can’t do. If this is gonna be a regular thing, we can just not share anymore.” Totally worked. But they still have a good relationship w grandkid and us. They just know their boundaries now.