Question on Tactical Voting (a real-world dilemma)

[muon2]

You are describing the bullet vote for a single candidate in a multi-seat race. Tactically this applies when you have a clear favorite in the race, but you aren't sure who the strongest challenger is that might block your candidate from being among the winners. The risk is that you would cast a vote for the other candidate and they would sweep ahead you your favorite. The bullet vote minimizes that risk.

If Grosso were your only acceptable candidate then a bullet vote is the clear choice. If you want to maximize unseating Brown then you should cast two votes for contenders who have a chance to do so since it helps out two possibilities towards your goal. From what you posted the analysis should come down to whether the risk of Beatty edging out Grosso is acceptable in order to have two shots at removing Brown.