@gardengait - Post 11 - apart from the 'old' SIM scenario I mentioned previously there's no obvious reason that I can see where a new/replacement SIM would be issued if merely adding more data to an existing plan.
Depends how you define 'upgrade' I suppose - feel free to add further clarification.
p.s. If for some reason you get a physical SIM at home, and you're within the 14-day cooling off period, then one option might be to instead upgrade to an EE plan with an eSIM, and return the physical SIM to BT. Alternatively, just post/courier the BT SIM to your daughter - though I appreciate this may not be timely and has its own risks.
