I’m a cross dresser, can I use water balloons as fake breasts in any bra?

So I’m considering buying a bra. I’d love a Calvin Klein bralete, sports bra thing, but I’m not sure if it would work. I know a push-up bra should work if I fill a baloon with sand or water but not sure about a sports bra.

Thanks for any help.
I’m a cross dresser, can I use water balloons as fake breasts in any bra?
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