If I were to go to Safeco Field while a Mariners game was being played and walk onto the field I would be among the Mariners, but that wouldn’t make me one :>)
” I would be among the Mariners, but that wouldn’t make me one”
Right you are, except there were no other apostles mentioned in Paul’s salutations at the end of his letter. All the people mentioned are meeting at a house church in Rome.