My puppy is being treated for scabies/manges right now. Should we start treating our other dog too?

We got our new puppy about a three weeks ago and we took him to the vet for severe dry itchy skin. His skin scrape test came back negative, but his vet highly suspects that he has scabies mites. My puppy is now on medication to fight off those nasty mites, which I still don't know where he could've gotten the mites from! We are starting to clean and sanitize our house and anything that our puppy have been on to prevent re-infestation. The thing is, we have a Pomeranian, who has been with our new puppy since day one! So far, the pom has shown no symptoms whatsoever. It's either our puppy got the mites from the pom or he is just not infected. Just to be safe, should we bring in our pom to treat as well? Or is he fine?

I have some experience with this I used to volunteer at a dog shelter and from my experience I think you should better to be safe than sorry there's a 50 50 chance that the pom could have it