Hi Jenny,
Not sure now,but Catalunya brought in a new law (a few years back) regarding the obligation for property owners to  obtain a "letting licence" from the local authority before letting holiday homes on a short term basis ie for a few weeks at a time.I am not sure if it is still in force? maybe other TF members will be able to confirm this? But if so,perhaps the local Police may also want to see that as well as noting the names of who is staying in your holiday home? Apologies of course if you have already obtained one. Goodluck