Big sis likes to interfere

i know this might not be the best way to go about it, but if all else fails, try reverse psychology ;) My baby sister liked to go and pick on the boys, all the time, and they had a lot of trouble doing homework, so i found her trouble point and told the boys for a few days they could pick on her like she picked on them, and they wouldn't get in trouble for it as long as when i say stop, they stop. Anyway, she didn't like it, she freaked and screamed and all that, it was always when she was reading, and then about 3 or 4ish days after the boys started in on her i sat her down and said to her well, you don't like to be treated that way do you? and no kept coming out haha, ohh and don't forget the buts, anyway i explained to her that the boys had a hard enough time with that stuff without her interfering with it all, and unless she stopped with them, they had permission to keep bothering her. It stopped for the most part, yeah there was the occasional day, but for the most part, it was all good after that.

Since someone else is with your son, why not greet your daughter and go for a walk or a drive to get an ice cream or out front to play hopscotch, etc. She's doing it because she comes home and he's getting special attention. Any attention is attention, good or bad, so she's playing for attention. Beat her to the punch and give her one on one attention and allow your son and his therapist to finish their time. When they are done, go in together and do something. Or bring her inside right away and have a project started to do with her... baking cookies, decorating the front window, etc.