Hihi,
Congrats on the Sennie. They are lovely birds, but, as you will discover, they are very different from QPs. Generally speaking, African parrots are much less outgoing and noisy than South Americans. I speak from experience: 2 Patagonian Conures make three times the noise of 6 African Greys!
I'm glad to hear that you are quarantining your Sennie. You just can't be too careful. Even if he is not ill himself, he may well be carrying pathogens to which P.B. is not used.
One piece of advice - and one that it always hurts me to have to give: don't let your new Sennie out of his cage for a good couple of weeks. I hate cages! On principle! But he must get used to his new surroundings first, new sounds, new smells, new people. If something were to spook him early on before he has got used to his new surroundings, he may panic and injure himself.
On the same note, make sure that, the first time you let him out of his cage, you do so at night with the curtains/drapes closed. There is no worse feeling for the dedicated parrot owner than seeing a beloved bird flying into a window pane...
My second ever Grey, a poor, badly abused bird, came to us with the name of Rupert. We felt we had to change his name, simply because, he would cower and scream with fear whenever we called it. Years later,
Induna is now a confident, healthy, happy bird, who answers to his new name with alacrity. (

My Big Bad Baby Boy!

) So yes, name changes work. If there is no bad history associated with his name, and no bad memories, then you could try adding your newly chosen name for him to Birdo for some months. Then, eventually, just stop using that name, calling him only by the new name.
After 40 days quarantine, it is important that you introduce the new Sennie to P.B. in the right way for them to accept each other.
I posted on this issue here just yesterday, so I hope you will forgive me if I am lazy and don't type it all out again.

I hope that helps.