sliding scale required for fluids offered

when we select fluids and the amount we have offered we can only select sips, 80ml, 150ml, 200ml, 280ml, 550ml, 1000ml and 330ml. there is no inbetween, so for example some residents have ensures that are 125mls but can only select either 80ml which is not enough or 150ml which is too much. this then results in a false amount of fluids being offered, we require this to be changed to a sliding scale like we have for the fluid accepted option so that it is more accurate