I think that would be nice, making the App even more flexible.
Maybe kind of 'swap mode' (like in Pendel Panda or Elixir2).
Having two 'parking positions' would probably make it more comfortable.
But this is just an idea ;-)
Manual pairings could reflect what you see in wizards event reporter. Possibly a scroll-able list of the pairings, long tap to unpair; and a scroll-able list of unpaired players, tap two names to pair, long tap to pair as a bye.