In the BRF who get the use of what tiara(s) is upto the sovereign. During the present reign The Queen has around 9 tiaras for her exclusive use (including Vladimir), she's loaned 3 to Camilla (Delhir Durbar, Greville, and Teck Crescent), and 3 to Kate (Halo Scroll, Lotus Flower, and Cambridge Lovers Knot). Camilla aslo has her family's tiara. Camilla has never been seen in the Teck Crescent and has only worn the Delhir Durbar once...she sticks with the Greville and occasionally her family tiara. Kate has only worn the Halo Scroll once (and I think it's still on loan to Cartier) and since being loan the Cambridge sticks with that one.
All that to say that during the present reign will probably only ever seen Camilla in the Greville and Kate in the Cambridge Lovers Knot...it's boring AF but that the way Liz rolls. Once Charles in monarch, he (or Camilla) can retool things. Camilla as consort would have access to all the tiaras and it would be up to her as to how they were loaned out. She could switch to a more mainland Europe model...free for all according to rank with a couple reserved for the Queen and/or Crown Princess...or she could stick with the "lifetime" loan model. Once William's king, Catherine will have access to all the tiaras and could retool things yet again.
The BRF really needs to switch to a mainland Europe model but could still reserve the biggest of the big guns for use by The Queen, The Princess of Wales, and the heir's heir (or wife of) if there was one. Liz is one stingy b*tch.
Sorry Thistle, I just noticed that you'd already responded.