Moving into a 2 dog home with my reactive dog

So I'm moving in with a close friend and his sister. They have 2 dogs. One that's an older calm dog and one that is occasionally/randomly reactive. He can chill with other dogs but sometimes he gets a burst of aggression and bark in another pet's face. He never attacks or anything, he just gets in their face. Both are male but neutered. My dog is an older female and has some medical issues. She is a pretty lethargic dog, always has been since I got her. She has only ever been aggressive around other dogs. She is a rescue so I don't know what her life was like before a adopted her.

When she was a lot younger she would be very aggressive if another dog got too close. But I've noticed she seems to have calmed down a bit with age. One time a friend brought his puppy over. I kept her in my room but she didn't seem to react to the puppy being nearby at all. Granted that was a puppy, we're looking at 2 grown dogs.

So, due to circumstance I have to move in when my current lease ends. Which is about 5 months from now. Rehoming isn't an option on my end. I've had my dog since I was a tween and I'm not willing to give her up. The other dogs I want to avoid rehoming. One my friend is very attached to, and the dog is very attached to him. The other is 14 years old, he was adopted after being rehomed previously. So I'd very much like to make this work.

I know scent swapping and parallel walks are a good start. I would just like to know if there are any other tips y'all can offer me. I would greatly appreciate it, thank you.