We tried to sign Lafferty before Van Veen, and I think Alexander played alongside him at Burnley, so I don't think there's anything to suggest we wouldn't go for him on that basis.
I don't think he's what we need right now though. As well as Van Veen and Watt have performed thus far I think they've been a bit of an awkward fit in our system, with one having to play out left. If we're replacing Watt I'd rather see a James Scott type (not James Scott I know he's at Hibs until the end of the season) wide forward.