I really enjoy seeing this tiara on other members of the Marichalar family! That's how family heirlooms should be used, imho. Years ago it was reported that Infanta Elena kept the tiara after the divorce, since it has been a wedding present and therefore hers. Also, she has worn it once after the divorce, at the wedding of Victoria & Daniel. So if that is correct, she still has a good relationship with her former in-laws and is willing to loan them her tiara.
It's also interesting, that the tiara can come apart and be worn as a Greek key necklace and as a laurel jewel. Ana Coronel de Palma y Marichalar wore it as a hair jewel above her bun, but I assume that the laurel part can also be a necklace or a bracelet. But given the differing patterns of the Greek key and laurel parts it's not really surprising that this is a lego piece. Have we ever seen the Infanta wearing parts of the tiara in their other functions?