Trying to help 20 month old and 3 year old get along and it's exhausting.

My son is 20 months but speech delayed and doesn't communicate well. We just moved in with my best friend who has 3 and 6 year old daughters. The 6 year old is so understanding and patient with my son. The 3 year however, doesn't like him (and I don't blame her) but my son will not leave her alone! He snatches toys, grabs her shirt, has pinched her, steals her food even if he has exact same thing, etc. And now she runs from him every time he comes towards her which is making it worse because he thinks she's playing a game. It makes me sad because my son is such a sweet kid and most of the time he's just trying to play, but he's obviously doing it so, so, so wrong...It's exhausting constantly running interference between them. When my son takes a toy I of course tell him no, we have to share etc and make him give it back and I know it's going to take awhile before he actually grasps the concept and for the most part this is normal... But obviously the 3 year old doesn't understand that and every time it happens she likes him even less which results in a vicious cycle of things getting worse. And the pinching thing happens when he's over excited and because it's when he's happy it's even harder to stop. Anyone have advice on helping them get along? :( via /r/Parenting http://ift.tt/2sJjoXJ