Shes having sex with her boyfriend without him knowing she has HIV? And wants to with other people? Now that really does have huge 'legal ramifications' if anything happens. Condom or no condom.
Further, if she chooses to have sex without a condom I understand that it is the duty of the doctor to inform her sexual partners, breaking consent, if she won't.
Yes, having an undetectable viral load makes transmission low-negligible, but even in people who take their anti-virals on a perfect daily basis your viral load can increase rapidly before you have another check and you will not know until you've been to your next appointment up to a year down the line. You cannot have protected or unprotected sex without informing partners (morally, and also legally if they catch it or find out) - most doctors would probably consider the risk of protected sex low enough to not break confidence, but they would probably consider the risk of unprotected sex with multiple uninformed people high enough to break confidence.