Lavery, who fired an impressive double in Wednesday's 6-0 thrashing of Leeds at the weekend after returning from his loan spell at Plymouth, and USA international defender Onyewu, were not registered with the club when the two sides drew 1-1 at Moss Rose in the original tie.
Gray will recall on-loan Arsenal goalkeeper Damian Martinez in place of Chris Kirkland, while winger Jermaine Johnson and midfield pair Jeremy Helan and Stephen McPhail are pushing for recalls.
Michail Antonio, Giles Coke (both hamstring), Lewis Buxton (groin), Kamil Zayatte, Martin Taylor (both ankle) and Anthony Gardner (Achilles) all remain sidelined.
- Sports & Recreation
- Chris Kirkland
- Jeremy Helan