The idea of willfully creating another entity to capture different parts of the market I don't think has happened elsewhere in PR run democracies. IE, like Pepsi taking over and marketing both 7-Up and Mountain Dew to counter Coke taking over and marketing Sprite (not to mention Pepsi taking over Tropicana juices to counter Coke having Minute Maid juices). Then maybe Pepsi could win majority market share with the combined sales of Tropicana, 7-Up, Mountain Dew, and of course Pepsi to counter Coke. So, perhaps the Conservatives will come up with or take over current existing parties (IE, take over Progressive Canada Party, Libertarian Party, Christian Heritage Party and have them as brands to the umbrella Con party) to increase their overall market share in a PR system. Yeah, I just don't see it happening. I believe they would find it easier to simply work on rejigging their main brand rather than wasting resources on creating or taking over smaller brands and trying to build them up. Plus supporting a party that's supposed to be a competitor is likely against some rule somewhere.
Sorry you have this backwards. They were two parties. They are uncomfortable together but reconfigured ONLY due to FPTP. That was exactly what the merger was all about. The only good argument for the merger was -- while we don't like each other we are dead in the water due to vote splitting under FPTP.
And absolutely they have been held together by the threat of FPTP. Remove FPTP and there is no force keeping them together. The fact that they would do better as two parties under PR is a bonus. They would be two parties even if they could only break even.