YOUR WILL
It is very advisable to grant a Will in Spain regarding assets (such as your properties in Spain),

in order to avoid any kind of problems arising from the differences between Spanish and the purchaser´s home country law (if not a resident) in succession matters and the execution of a Will from one country to another.
So it is always sensible to grant a Will in Spain, in which foreign people state that the applicable law is the law of their country, and they can decide to leave their assets in Spain to whom they would like according to the personal country law.