No, they start with the Order of Isabel la Catolica like with her aunts, but back then the Order of Carlos III didn't accept women... I don't know if they want to have the possibility of granting her another decoration in the future, or if it's a matter of this Government, which is very "particular".
Queen Letizia still holds the Grand Cross of the Order of Carlos III, even though her mother-in-law held the collar, and now even the Golden Fleece. Not for her 50th birthday, not for her 20th wedding anniversary, nor for her 10 years as Queen.