Owners with Reactive Dogs – How’d You Introduce a Second Dog?

For context – my dog very recently became "mildly" reactive after essentially not giving two hoots about another dog. As soon as it started, I began working on it and we're making progress. Before this happened, I was looking out for rescue dogs I could possibly foster and then adopt but have obviously paused this while we get the reactivity under control. I'm fine to put the search off indefinitely as I'm in no rush but was just wondering how this affects my plans?

So for those of you with one reactive dog, how'd you introduce your second? What was it like for them? Did it take time? Would you recommend simply not getting a second dog at all? All input is welcome!