My name is Lundy!

Lundy is a mixed shepherd. We adopted her from a rescue with another puppy. She is 3 1/2 years old. She is particular about certain people especially strangers but she has never bitten anyone. About 6 months ago we adopted another puppy and that’s when things changed. She has attacked her sibling 3 times since we got the new puppy. We think it might be protective instincts. We have tried everything to fix this problem but
Nothing has worked. We just think she needs to be in a home by herself. She is so loving towards us and it just breaks our hearts that we have to give her up. She doesn’t require a lot of exercise. She loves to walk around the block and just lay in the couch. We would prefer she be an indoor dog. We have a doggy door that she freely can go in and out of. She wouldn’t get into any trouble if you have to leave here for periods of time. She is unable to do extra activities cuz she’s had a knee revision . She feels secure in a crate.