I'm 36weeks with our first take-home baby and I'm wanting to get a pump. I have a manual pump already but am anticipating that I'll want to pump quite frequently (for a variety of reasons) so would need an electric one. They're SO expensive here and my cousin offered me her second-hand Medela Swing...I know I've read that you shouldn't use second hand breast pumps b/c risk of infection and I definitely don't want to put LO at risk for anything - but everything I've read says there is a risk for HIV and CMV transmission (which I'm not worried about as she's clear for both) and a LOT about mould.

So my question is this: if you have an open system pump where milk can backflow so parts of the pump that CANT be cleaned/sterilised retain milk particles and this creates mould, isn't that bad for any baby? what would be the difference in me buying my own pump for LO and using someone else's (except obv that it's my milk particles vs hers)? Surely either way, there will be mould in the milk over time?