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Could it have something to do with the BK Kids Club?
Is it the human race club?
Codename: Kids Next Door?
Probably a longshot but could it be "Miss BG"? There was a treehouse and BG had a little brother, and one episode's plot involved embarassing photos, though it played out differently from the one you describe and the animation looks more modern.
So sorry it took so long but i didnt think anyone would ever reply! Actually logged back on here to delete my question lol but yes @kmsikes it is the human race club! The episode i was thinking of was called "casey's revenge". Im glad someone else has heard of it! Thank you for your help guys =)
Not sure if this is a movie or show, I just remember watching it on vhs tapes. It involved a club of kids that met in a tree house or clubhouse and they had certain problems like getting along with siblings or something. For example, the one I remember is this little brother went camping and took and picture of his sister squatting (it was a children's show so it didn't show anything graphic at all) and he was gonna put the slide of the picture in during a school dance or something and they end up making up or something like that. Another storyline ended with them writing thank you notes for cookies or something. I want to say the name has something to do with humanity society or tree house society but I've Google all variations of that.
Thanks in advance, new to this site and this is awesome!