The following rules related to wheelchair players have been extracted from the ITTF handbook:
2.8 THE ORDER OF PLAY
2.8.3 In doubles, when at least one player of a pair is in a wheelchair due to a physical disability, the server shall first make a service, the receiver shall then make a return but thereafter either player of the disabled pair may make returns.
2.9 A LET
22.214.171.124 if the receiver is in wheelchair owing to a physical disability and in service the ball, provided that the service is otherwise correct, 126.96.36.199.1 after touching the receiver’s court returns in the direction of the net; 188.8.131.52.2 comes to rest on the receiver's court; 184.108.40.206.3 in singles leaves the receiver’s court after touching it by either of its sidelines.
2.10 A POINT
2.10.1 Unless the rally is a let, a player shall score a point
220.127.116.11 if both players or pairs are in a wheelchair due to a physical disability and
18.104.22.168.1 his or her opponent does not maintain a minimum contact with the seat or cushion(s), with the back of the thigh, when the ball is struck;
22.214.171.124.2 his or her opponent touches the table with either hand before striking the ball; 126.96.36.199.3 his or her opponent’s footrest or foot touches the floor during play.
188.8.131.52 if, where an opposing doubles pair includes at least one player in a wheelchair, any part of the wheelchair or a foot of a standing player crosses an imaginary extension of the centre line of the table.