Help with buying someone a bra pls

Hi

I'm caring for my mom and we need to get her a bra and I have no experience and it's easier for me to ask reddit than anyone in person. Please help :)

She's got a big back and a handsomely-sizeable rack to go with it. This, among many other features, makes her a delight to hug

Is underwire better? I'd suppose not but 🤷🏻

What do you wear to a bra fitting appointment? Do you get your preciousnesses out for assessment?

How do I work out her cup size? I guess it's gonna be like bountiful ddoubles but I dunno if D or f or g 🤷🏻

I think I get how to do the undercut sizing, like, the numbers, but any tips appreciated!

Anything else you think I should think about? Any other tips?

We're in UK if that helps

Thank you for your help!

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