Qualifying draw is going on, so lucky loser will replace him, if he is out. If the qualies hasn't started, 1st alternate takes his place.
It happened at RG f.e. this year. Monfils withdrew 3 or 4 hours before first match Q, Karol Beck moved IN as a 1st alt. and his place in Q draw was replaced by someone else. But if Monfils had pulled out after some matches started, LL gets his place as far I am concerned.
Thanks for the explanation!