Yep, we have something similar. When we bought our place, the deeds had to show that there was a habitable house on the property as-well as it showed the two new almacens the previous owner build illegally. Result: House deeds that show a house and almacen where applicable. I helped a local office with planning permissions for a few months and there was a 5-year rule in certain case's. Now, I CANNOT BE QUOTED ON THIS  but if a building has been standing for 5 years or more, irrespective of what it is, it should, could,can become legall for the use it is at the time registration.

NOTE: A POSTING IN A FORUM WON'T STAND IN A COURT OF LAW

There is at times a fine involved at the most but my suggestion would be that if a property has a legal Almacen on, then that is half the battle won. No they don't like or allow you to convert, should they know, but at-least they cannot force you to convert back to more than an almacen so at least you won't lose all your cash should it go wrong. Its a gamble but with time can be overcome.

Hope that confuses the issue even more.

Cheers