Behavior Have one pig left, deciding if I should keep my new pair?

A little background, I've had guinea pigs for 10+ years since my original pair, and have adding one every few years so I always have about three, sometimes four. I had two pigs but one passed away a week ago, the remaining is about 4 years old. I decided to get another pair as companionship and so they would have each other in a few years when that pig passed.

So now I'm debating if that was a good idea ... I had them in quarantine for a few days, I know I should wait longer, but so no obvious signs of sickness/scratching. I introduced them in a neutral space and after about an hour or two of sniffing/teeth chattering/nipping at ears/etc they seemed to find their place and that has stopped. My older pig wasn't the dominant when I had three pigs, but the dominant one passed so she became it. She doesn't really seem to care for the new pigs, and seems to like terrorizing them. At times they can be side by side, but then she'll decide to chase them away - there is no chattering, etc. Sometimes she'll go out of her way leaving her house to chase one away, then going back.

The main reason I got the new pair was for company, but my old pig doesn't seem to appreciate them, and I'm not sure it's good for the little pigs. They do seem to like my big 30x90 cage when the older one is asleep and would probably be great by themselves. I also have the issues of noise as they're being chased around with my apartment neighbors.

I'm thinking my old pig just isn't one who really needs/wants companionship and if it would be best for all involved if I brought them back and they could find a new home, but I'd like to hear any input. It's been four years since I've gotten a new pig, but I don't recall this situation introducing her.