We present a theoretical study of adhesion-induced lateral phase separation for a membrane with short stickers, long stickers, and repellers confined between two hard walls. The effects of confinement and repellers on lateral phase separation are investigated. We find that the critical potential depth of the stickers for lateral phase separation increases as the distance between the hard walls decreases. This suggests confinement-induced or force-induced mixing of stickers. We also find that repellers with stronger repulsive potential tend to enhance, while repellers with weaker repulsive potential tend to suppress adhesion-induced lateral phase separation.