I need some help with my itinerary FRA-YYZ-LAX-OGG / LAX-YYZ-FRA.

I want to take a flexible business class fare FRA-OGG (PFFA8) and ideally a latitude fare LAX-FRA for the return to use some of my e-upgrades (the OGG-LAX flight is already taken care of otherwise). Looking at the fare table on Expertflyer - this would obviously be the return portion of a FRA-LAX fare - I only see fares with NC, RC and FF in the name, from my experience this stands for no cancellation, restricted cancellation and fully flexible, combined with various booking classes. There is no information in the fare rules to which fare class each fare belongs. I have already used Powertools and while the FRA-OGG portion shows up fine, the return always comes back as Economy - Flex with the "FF" fares (no matter if I use the lowest available booking class V or a higher one like U or M). This is the deeplink from Powertools that takes me directly to aircanada.com with all flights I want already selected (already cleaned up the 12h times from matrix): Link

When I use the multi-city option on aircanada.com, there is no way to get the flexible PFFA8 fare, only the non-ref PNCA8 which I don't want. However, for the return it allows me to select a latitude fare and this shows up in the fare details as VLDXDXLT. This fare does not appear on Expertflyer. However, when I replace the references to VLFFB4 in the link with VLDXDXLT it no longer works, it takes me to the page where I need to select flights.

Any suggestions on how to get a latiude fare for the return?