Does anyone know how to train two puppies to get along???

My two, Sammie (7mos) and Maggie (4mos), play and fight but the fighting sometimes becomes really aggressive to the point where I have to break them up. Sammie is also very possessive of her belongings in which I totally understand but I would like her to stop growling at Maggie when she just walks by.

Any ideas???? I'm kinda stressed about this and really want to keep both of them. I dread the thought of giving one up because of this problem.


Thanks!!!!