As other posters explained before, Queen Fabiola's estate was officially bequeathed to the charity Help Fund of the Queen, which is currently chaired by Queen Mathilde. It has been confirmed that furniture, jewelry and letters from King Baudouin that were part of the estate are also among the items now transferred to the charity.
I fail to see what the Help Fund would do with a tiara or a necklace that were worn by Queen Fabiola, but I suppose they could be auctioned (we probably would know by now if they had been), placed in the Royal Collection as a museum item , or transferred to the Royal Family for personal use in public events. The latter has not happened yet, except for items like the Wolfers tiara, the waterfall diamond brooch, the pearl and diamond earrings, or the ruby and diamond bracelet which, apparently, were given by Fabiola to Mathilde (or Philippe) while she was still alive and, therefore, were not part of the estate that was left to the Help Fund.
Personally, I don't find the Franco wedding gift tiara a particularly valuable piece that is worth keeping for use by future generations of the RF, especially given its controversial origin. I will be far more upset if it is confirmed, however, that Queen Paola has left the Art Deco tiara to Princess Astrid. Although the Art Deco is a modest tiara by royal standards, it was worn by three queens (Élisabeth, Astrid and Paola) and it was Mathilde's wedding tiara, so it deserves to stay in the main line.
