Im doing the 40 hour famine, and to raise more money i have an idea. will it work?

i want to stand outside the library or some place public and shake a tin can with my friend for the 40 hour famine. whats stopping me is that i think you have to write down everyone who donates to you. but the other day i was doorknocking and a lady said "oh i dont need a receipt", but i wrote her down anyway. is writing them in your book necessary, even if they dont want a receipt? because i thought at the end i could just put it under like my name, that i donated the money that i got from the tin can. just so the amount of money is up to date with the amount of donations i've received. is anyone still following me?