The architect is in Madrid though and we need someone in the Costa Blanca for the work.
So, approach the College of Technical Architects/Aparajedores for your area and ask them to provide you with some local contacts. They keep a database of professionals and their specialisations.
We all like to do things ourselves as much as possible but if you needed an operation you wouldn’t perform it yourself, would you? You’d employ the services of a surgeon I hope 😉 You weren’t averse to employing a solicitor after all.
p.s. Technically, raising floors falls under the category of Major Works not Minor.