Dad here, 'tis hard watching them grow up. I gave my son a razor just over 2yrs ago, he needed it not at the time but... They grow up fast, 2,5 years later and I occasionally ask to borrow a blade or a bit of foam. Now 15, and he has had an allowance for clothing for a couple of years, buys on line, and really does spend it on clothing, including his trendy branded underwear.
As for emptying the washing machine/clearing the line... Until a couple years it was really easy to separate washing into my, grey saggy M&S Y fronts (well yes M&S, but mostly blue and why spoil a story), mum's granny pants, dd thongs and lacy "bits" and the now sporty elasticated boxers for ds. Well.. perhaps. All Y fronts are still mine and mine alone, sporty "branded" boxers might be on loan from ds to dd but no... got told in no uncertain terms that they are "hers" and the thongs might be on loan from dd to her mum (only on loan but go in her drawer as not sure she brave enough to actually buy then), and heaven forbid, some of granny pants (think they be a bit more "slinky") actually belong to dd? The end of the world is nigh...
And I do my best with the bras, underwired, easy, = dd, can "recognise" a few as belonging to dw but many have to be left out for "collection"
So, please OP empower her, or allow Ex's partner, to get her whatever she wants or rather feels she "needs", it is certainly part of growing up and with the benefit of hindsight part of parenting. You will all have a giggle about it in a couple of years, esp when you try to sort the washing.