If your flexible you can fly YUL-ZRH on LX on Sept 26... from there looks like you need ZRH-FRA-LEJ... which is also available on the 27th (your arrival date into ZRH)
ZRH-YUL is available on LX on the 17th... Option via BOS on the 18th but involves a 10hr layover...
Not your exact dates, but that what booking desirable routes in the 5 to 6 month range will generally look like..