See text in the official website which describes them as being "
The collection of Crown Jewels for use by the reigning Queen". It is reasonable to suspect that a request from Queen Margrethe to use any of the jewels should be taken as a command. A member of her household probably is the appointed person to communicate these requests with Rosenborg's officials. I would expect for security and logistical reasons that these requests are made well in advance of the date the jewels are to be worn. Queen Margrethe said in a documentary that she tries to not keep them gone for long.
https://www.kongernessamling.dk/en/rosenborg/room/the-treasury-section-3/