Title encumbered with a right of use.

The house I wish to buy has a problem, the 'copia simple' shows an encumberence;
Gravada con; Derecho de uso ...
(Encumbered with; Right of use...)
This is in favour of the current owners ex partner.
She is not a co-owner.
The owner is trying to locate her but she has disapeared.
What in fact does this 'right of use' entitle her to do if she returned?
It seems an odd thing that a complete stranger has the right to move in with the new owner.
Any help appreciated.

Good afternoon. From the information provided it is not possible to offer you any advice. Please send me a scanned copy of it to my e-mail address. We will have a look at it and advice you accordingly.

A copy of the copia simple.