Okay, good.

If I for some reason cannot convince my in-laws to do an obedience class with her, what can/should I do when this happens? And what can I do to prevent it from happening.

My Mother-in-law is certain that if they play outside a few times it'll be fine, I don't think she sees how Strummer has become possessive of her, not just the house and toys. However Strummer oddly enough didn't mind when my dog was at her food...