You had to do what you found right, both for your family and for the bird. You did that. The bird had been seriously abused. That was not any of your doing.
I have all of the birds you have. I do not have a meyers, but a senegal is quite similar, and I have one of those. My senegal has never been abused, but she doesn't like most other people. She loves my avian vet, and she is even nice to the staff there. She is generally sweet with me. She can still be sweet with folks at the bird store. She is very bratty with my children. As a species, senegals are generally more prone to becoming one person birds than are meyers, but everything depends on the individual.
My maxi is as sweet as the day is long. I can take her around handicapped people and very little children and she is gentle with everyone. However, had she ever been abused, she would not be who she is today.
Among my birds, the maxi is an exceptionally good family bird, and the senegal is not, but she and the kids just have a truce. They don't mess with her, and she doesn't mess with them.
My maxi was 13 when we got her. The secret was selecting a bird that was already sweet. I have respect for people who rehabilitate birds, but that is not for me, at least not at this point in my life. I have a hard enough time not messing up birds that have been handled well.
There is something to be said for getting another South American bird since that is what the rest of yours are. My birds from South America all seem to understand one another very well. I'm not saying they all interact with one another, because some of them don't, but they understand one another and they don't fight because they stay away from each other when that is what needs to be done.
I only let my two African birds out together. Long ago, when I only had one African bird, one Australian bird, and one South American bird, I let those three all out together, but all of the birds were clipped, so they stayed away from one another. Now that my birds are flighted, I would be afraid to have the senegal out with the South American birds.
African birds do not flock with other species of birds. Most South American birds do flock with other species of birds. I think this makes some difference in how they interact with one another. Nevertheless, my African birds really do seem to understand one another very well, and they coexist peacefully when out of their cages at the same time.
My only Australian bird who is home presently, the bourkes, would go right up to any bird and never realize it would kill her. I notice that Cannary's POW is exactly the same way in the store. We are always having to get her away from the macaws or anything else. Since my South American birds don't ever hurt the bourkes, and, in fact, let her do things they would never let the other South American birds do, I am hoping they will be the same way with the POW.
Understand, though, that not all senegals are like mine. Tippa's senegal seems to be gentler than his little conures, so, as I said, it is all individual. I will say this about poicephalus, they can be the sweetest things ever, and they can be unpredictable.
Just pick a bird you've visited a lot and are certain fits what you can handle.
OH, and it has been my experience that female pionus are, as a whole, gentler than males.