When I last responded to you, I promised to get back with ideas about introducing you to a new cat companion, assuming that Themselves would be bringing one into your territory in the not-too-distant future.
So here goes.
First and foremost, follow my entry, May I Introduce . . . A Cat! It is a slower-than-most introduction process because I find most humans to be in too much of a hurry and thereby they set the stage for future trouble.
So take my advice and go slow. You are the resident cat and the elder, and thus you set the pace for the process. Tell Themselves to be patient. The newcomer (likely a kitten or very young cat) will be more adaptable.
Other than following these instructions, there are only three things to keep in mind. First, you need unrestricted access to important parts of your existing territory to the extent possible. This means that if the living room is a key viewing area for you, it should not be the newcomer's domain. Instead the newcomer should be set up in another, safe room. And second, you will need assurance. So at least one of your purrsons should commit to giving you sufficient daily attention of the kind you desire - regardless of how tempting it may be for both of them to focus on the newcomer. Besides, this will be a good way to monitor your status so that the process proceeds at a pace you can handle. And third, the best time for a newcomer is when things are stable in the household - no renovations, no emotional crises or anything else to turn everything off-kilter.
That's it for now, dear. As for you question on roaming cats, I should be able to get back to you much more quickly on that.
Purrs to you,