Aggressive/Reactive dog training in Houston

Hey everyone,

Looking for some insight into good trainers or behaviorists around Houston to help with dog-dog aggressiveness and reactivity.

For some background, my girlfriend adopted this rescue probably 3 years ago and she is the sweetest dog, but so timid. She’s a GSP blue heeler mix and is probably about 40 pounds. We adopted her when she was about 1, but for the first 6 months of her life she was locked up in a barn on a chain.

Fast forward to now: between my brothers, my parents, my aunt, my girlfriend and myself, we have 8 dogs and we do a lot of family stuff with our dogs.

Our rescue, for some reason does not get along with the other girl dogs that are smaller than her (border collie mix, corgi, and toy poodle). Given, Maggie is extremely timid and the border collie and corgi are extremely loud and have strong alpha tendencies, but Maggie will often lunge at them and then a fight breaks out. It’s the absolute worst thing. But she gets along with my brothers dog (we are roommates) and she is a lab-coonhound mix.

Anyways just kinda wanted to put this out into the world. We love our dog and want to find a solution, but my family just tells me to get rid of her and I just don’t want to do that I’d rather try.

Any advice is helpful and welcome. Thanks ahead of time for your input. I’ve always been so good with dogs, but have never experienced having to train something like this away and don’t have the slightest idea of where to start.

I’ve also attached a picture of her with my dog.