Boot camp letters

So I’ve noticed I’m getting way more mail from my SO while he’s in boot camp then his parents are getting. I like to tell them when I get some so I can tell them how he’s doing but they just kinda get passive aggressive because they haven’t gotten as much as me. Should I continue to tell them every time I get mail or just keep it to myself for now on??

I really don’t want them getting upset with him while he’s away .