Chose author when creating post

Hi there. I have a blog/bio-thingy that I write in sometimes, but when I do I actually present myself as 3 different authors.
Lets say Mr. A, Mr. B and Mr. C…

In short:
As Mr. A I write about family stuff concerning my son that has a handicap
As Mr. B I write about the creations I make in the kitchen. Baking takes my mind of heavy stuff that comes with Mr. A
Mr. C also has a hobbie but that concerns motors, the sea etc and he needs a different site(user)

I am guessing there are smarter ways to do ths, but I went ahead and created 3 user accounts (1 as admin and 2 as authors) all with different emails….

When I write a new post it allways shows as if admin account (Mr. A) made it, but if I go ahead and edit it, I can then edit user from Mr. A to any of the 3.
I am always logged in as admin (Mr. A)

I would very much like to chose author directly when I am creating the post.
Isn’t that possible?