The present invention relates to a container adapter (9) for a medical delivery device (1). The medical delivery device (1) has a container seat (53) for holding a container (8) in a predefined position, a dosage chamber (61), a dosing mechanism to transfer a liquid from the container (8) held in the container seat (53) to the dosage chamber (61) and a lock mechanism (530) adapted to prevent operation of the dosing mechanism when no container (8) is held in the container seat (53) and to allow operation of the dosing mechanism when the container (8) is held in the container seat (53). The container adapter (9) comprises an adapter container seat (91) arranged to hold a container (8) in a predefined position； a joint structure (92) arranged to be detachably positioned in the container seat (53) of the medical delivery device (1) and to connect the adapter container seat (91) to the dosing mechanism of the medical delivery device (1) when the joint structure (92) is positioned in the container seat (53) of the medical delivery device (1)； and an unlock member (93) adapted to activate the lock mechanism (530) of the medical delivery device (1) such that operation of the dosing mechanism is allowed when the joint structure (92) is positioned in the container seat (53) of the medical delivery device (1). The present invention also relates to a delivery assembly comprising a container adapter (9) as above introduced and a corresponding medical delivery device (1) receiving in its container seat (53) the joint structure (92) of the container adapter (9)； as well as to a method of delivering a liquid to a patient from different containers (8), a first container being preliminarily arranged in the adapter container seat (91) of the container adapter (9) and a second container being positioned in the container seat (53) of the medical delivery device (1) after removal of the container adapter (9) therefrom.30 Nouvelle Demande De Brevet International F Hoffmann-La Roche AG ； H
