Who get the rights over a screenplay? How can i avoid that the director and the producer, who want to sign an agreement with me, don’t claim all rights?
The rights over a screenplay or choreography go to the writer of it, therefore, in this case, they go to you, having taken care already of depositing it at the SIAE. I don’t know if the other parts involved are aware of this first deposit or if there have been some modifications to the initial project. If the screenplay deposited is identical to the current one, it would not make sense to make a new deposit at a notary, unless the other parties are aware that you have deposited it on your name.
If, on the other hand, some modifications have been made, then all the people signing a new deposit at a Notary could claim a new right on these changes and they would all become co-authors. The risk you are incurring is not to be losing your rights, but to see them reduced due to the participation of others, such as the director and the producer, who would have in any case rights over the work to be produced. The best solution, probably, is to go to a Notary to underwrite an agreement between you regarding the sharing of the rights.
It is obvious that you will not be able to put up the screenplay by yourself; therefore it is inevitable to give a sharing of your earnings to who will be able to produce and direct the play, as you will have to pay the actors and any expenses related to the play. It is vital to clarify all these matters before starting, even regarding the moral right of being recognised as the author, which, I think, it is very important to you. In the agreement between you, it could be indicated that you will be the author to all effects, as the others only take care marginally and in the realization of the play.