A device, kit, and method for transferring a liquid medicament from a supply container to a flexible reservoir container are disclosed. The device may comprise a compartment unit and an adapter unit. The compartment unit may have a sealingly closable chamber, arranged for housing the flexible reservoir container and for being fluidly connected with a pump mechanism. The adapter unit may have at least one transfer passage for transferring liquid from a supply container connected to the adapter unit to the flexible reservoir container, and a separator arranged in the transfer passage for separating gas bubbles from a liquid streaming through the transfer passage. The separator may be fluidly connected to the chamber.