Thanks Stephen.
It depends on whether you mean "timeshare" in the proper sense, or a specific legal agreement between various genuine owners. If the latter, then there was presumably an occasion when these people signed for their share of the apartment at notary, or a less formal legal agreement drawn up by a lawyer. Either way, there should be a legal record in the escritutra, or in a contract of some sort. The best place to start is with one of the other owners, or if you don't have their details, then the administrator (or management office if timeshare) of the complex.
Start by telling me which complex.
