Hmm... maybe some horny swamp gas could work? lol. A "fuck or die" situation or sex pollen stuff like in some fanfic tropes.
And yeah it would also have to be a B!Logan route/event with a way to convince him to go to the swamps. From there a variant T!Logan from another timeline would appear. This variant T!Logan would have to be the one who investigated what was happening to the werewolves in his world at the swamp and why they were being controlled by the swamp vines or something, but he stumbled upon a portal that sent him to our B!Logan routes world, and maybe inhaled some... horny swamp gas along the way. And then fucking ensues.
Or just I dunno, maybe a non canon route would be easier lol. And just have the player go to the misty swamp and see a scene like this. Maybe it would be a hallucination or a dream and we would suddenly wake up alone in the swamp afterwards.