Rehoming dog advice

Hi all,

After some research, I wanted to seek some advice on this subreddit too.

We have one dog let’s call her dog 1 and we decided to rehome a dog from a charity, let’s call her dog 2.

They both get on very well and we have had dog 1 since she was a puppy. Dog 2 is very sweet and kind, however has issues around resource guarding which we are working on. But today I took both dogs for a walk and dog 2 was very defensive to runners, almost reacting towards them? Is this due to a lack of exposure? Is it trauma of the dog?

Dog 2 has also taught dog 1 to be very very barky when dog 1 isn’t initially quite barky, I’m very anxious as dog 1 has a good routine (obviously I know due to her being used to it) but I’m afraid that it’s chopping and changing her routine too much and dog 2 is teaching her some unnecessary traits. We have a dog walker that comes and I am petrified that dog 2 will be aggressive to other dogs that our dog walker has which then will make it very difficult for us as we need our dog walker.

Additionally, we know the 3-3-3 rule and dog 2 has been with us for a few weeks but just overall very anxious and want to give dog 2 a great home.

Edit: just wanted to add in that she meets a lot of dogs and is ok with them but some she’ll lie down then launch and them and show some teeth? Again is this trauma to something? Dog 1 is 1 years old and dog 2 is 2 years old!

Open to any advice!