It seems to me that you can't give up your rights to one throne (France) and marry into another family (Spain) with a reasonable expectation of getting close to the throne there, and then decide that you want to ignore all this at a later date.
I believe the last genuine claimant of the Bourbon line died without male heir in 1936. At this point, the right that the Bourbons had to the French throne moved across to the Orleans Branch. Louis Alphonse's line is a part of the Spanish Royal Family and out of the French one.
I believe it is the same for The Bourbon Two Sicilies line. The second son of Pr Alfonso, Head of the Royal House of BTS, Pr Carlo, became an Infante of Spain on his marriage to Infanta Maria de las Mercedes of Spain, and gave up any rights to the BTS line. This, as with the French case, was because the Spanish line kept looking as if it was going to die out, and there were only female heirs. When these Infantas married it was important that their decendants were only heirs to the Spanish throne and didn't muddy the waters by also being in line to any other throne . It is wrong to say, therefore, that Pr Don Carlos (who is married to Pss Anne of Orleans) is the Head of the Royal House of BTS. (The Don in his title gives it away - he is in the Spanish RF.) When Pr Alfonso of BTS's eldest son (Ferdinando) died without a male heir (1960), the right to be Head of the RH of BTS skipped over Carlo's line (who had 'abdicated') and landed on Pr Ranieri, the third son. With the death of Pr Ranieri's only son, Ferdinando, just recently, the Headship of this family passes to Pr Carlo. He is Fernando's only son - and at present he only has 2 daughters, I believe. So there may be problems with the succession in the future if this situation does not change!
I do not believe that King Juan Carlos of Spain supports the claim of either of his family members to the hypothetical 'thrones' of France or the Two Sicilies. After all their ancestors gave up their claims to become members of the Spanish Royal House.
