The ducky was too Horribly Obese to walk; it had to supplement its legs with a unicycle.
to suppliment - like 補充, but the nuance is that you are filling a vacancy. For instance, nutritional suppliment. Substitute teacher. Assist in the completion of something (I helped write the speech). To make up for (i.e. Mitsubishi bank loaned money to Toyota to make up for their shortfall) みつびし銀行はトヨタの赤字補いました。
to suppliment, (a shortfall or deficit) or replenish (fluids, vitamins to replenish strength, restock the store-room) - it's like 補う, but the nuance is that you are restocking a supply of something which has dwindled.
You use your HAND to capture,
but you use A DUCKY to supplement your bubble-bath.
補う 補強 補充する 補遺