Oooh Fiona... I don't know if it's just me but boy are you nice!

We will be in this situation in a couple of years...so ask me again then ... but I cannot imagine tiptoeing around all morning. My feeling would be, if your DSD wants to lie in till 11 that's fine but not at the expense of everyone elses' comfort.
IMO it's worth keeping in mind that other people live there too. If it's causing discomfort to them you or DD to keep it down for that amount of time, a compromise would seem fair.

You sound as though you get along well with your DSD.. maybe you could talk to her & find a time that suits you both, for things to stay quiet until then, say 9am?..after that she would have to make do & sleep if she can but without an expectation of quiet?

(I don't know how your 2yo DD copes with keeping the noise down lol....in fact how do you manage that?)

Good luck!