I booked three one-way tickets to MAD in C via MUC earlier this summer but kept watching for availability in LH First. As other have mentioned, if you are patient there are good chances to get a seat in F two weeks prior departure. Unfortunately in my case on the day I wanted to leave there was only two, and not three seats from YUL to MUC, but there was room from YYZ. I took them and next week we will be trying F for the first time.