Dealing with a toxic in law

So I have 3 other kids from two other relationships ..a 11 year old girl and one 8 year old boy and a 7 year old boy whom I love just as much as my other two I have with my spouse ...but every time I get my kids to spent time with them she never says hi , goodmorning or even try to be nice n I am very overprotective with them because I know how horrible people can be . n for some reason she has this mean mood towards my 11 year old. .. and every time I tell my spouse why does your mother have to say that to my daughter or be that way.. he always makes a face of tiredness .. we have had many talk many. N it's always her still trying to win something ... n I am just trying to fix it