hi willy46 here
yes you can use them few times,best way I do it.first time use new bubble E,I send -when I do sase do not seal bubble e.use masking tape leave stick cover over the flap.where you usely take of THE seal..so when person gets sase.then they can seal it right.and use labels that can cover another label to return.so use same size label. to person sending them back to you. return them
or hand write same space that label where it would fit.

EVEN FOR TRADING can do this way,can turn upside down so the stamp area will be fresh corner. I send extra stamps in case too.over 100 grams more,they alway be very helpful at post office.
willy46