Abstract: An adjustable overlaying interface for adjusting a prosthesis to a liner worn over a residual limb of a user comprises a sleeve, an inflatable bladder and a fluid-providing device. The variations in volume of the residual limb is compensated by using the fluid-providing device to inflate and/or deflate the inflatable bladder. A kit for adjusting the prosthesis to the residual limb comprises a liner and the adjustable overlaying interface. A method for mounting the prosthesis to the residual limb of a user comprises installing the adjustable overlaying interface over a liner donned over the residual limb of the user, at least partially inserting the residual limb wearing the liner and the adjustable overlaying interface within a socket of the prosthesis and inflating or deflating the inflatable bladder of the adjustable overlay interface to compensate variations in volume of the residual limb.