I am going to try to do a summary on the topic, though all are speculations of the press, and still there is no real information.
According to the press, the fortune of this man would be approximately 30 million Euros.
In his testament he arranged that the half of his fortune was to create a foundation, under what he has specified and that would be directed by the Prince. The money is not for the Prince but for the foundation, the Prince is only the person who has been chosen to coordinate it.
Another half would be divide between the Prince, Princess and 8 grandchildren of the King.
If the Royal Family was not accepting the heredity, according to a information, this one might go away to Israel.
According to the laws of the Balearic Islands where this man was living, if they were accepting the heredity 68 % (an economist speaks about 82) it would have to be to pay tax, to it there would be necessary to add the payment of other legal steps and of the lawyers. The final heredity would be small, and even an expert in economy has managed to say that it would remain in nothing.
The Royal Household still is studying all the information to decide if they accept it or not. In case of accepting it, the Prince and the Princess already have said that they would give to charity what was corresponding to them.
If they resign, the pricipal problem is that the foundation that would benefit to the society would not exist.
Another problem is the heredity of 8 children, who do not have the legal age to take decisions. Their parents are thaeir tutors, but according to the spanish laws, cannot take decisions about a heredity, without the authorization of a judge.
It will be necessary to wait a few months to know how concludes everything.