> The main benefit of FPTP, for third parties, is that they can hijack elections by acting as "anti-tiebreaker" (Threatening to turn their nearest ally into a lose by joining the election, unless that nearest ally adopts their platform). This is why third parties generally (and openly) advocate for FPTP.

This isn’t true in the U.K., the only country where a third party recently tried electoral reform in a country with FPTP. The Liberal Democrats wanted to get rid of FPTP.

True, but then the Lib Dems were succeeded by UKIP as the third party and the electoral threat they posed to the Conservative Party was a significant factor in putting moves to leave the EU onto the Conservative Party's agenda despite its leadership's reluctance.

Of course, without skewed vote shares due to FPTP and with a limited choice of realistic coalition partners for a future government, that third party can achieve exactly the same thing through coalition bargaining anyway.

Interesting idea, but it definitely doesn't pan out that way in Canada. The NDP and Liberals happily knee-cap themselves into a vote split.

Though there is also some precedent in Canada with previous Conservative party mergers.