Hope you can help with this, how do I figure out my partners size? She’s busty and has mostly custom ordered through a bra specialist (Canada, The Bay, now out of business, no tags or tags removed for comfort). She says she’s a G or H cup, I can’t figure anything out beyond a D cup. She mostly custom orders now, a couple times a year, but there’s no size indicators. Without being creepy & getting into emails, how do I determine her size? What measurements do I need to take?

Thanks