why the err ? 1 should be ok a neutral one , they all sit round the table maybe have a coffee while they discuss the deal with the independant solicitor .

get all the legal paperwork sorted etc etc.

Meet up on completion date have another coffee round the table whilst signing all relevant paperwork , before exchanging and handing keys over to each other .

1 bill rather than 2 solicitors trying to stretch it out so they can whack the costs up , and you can bet your life 2 would make a heck of a mountain out of it ..
be the classic well i will write to there solicitor and ask for this and ask for that then i will write to you and let you know , and on it goes ..

Quicker and easier i dont know why people make such a major thing about buying houses Its not technical or rocket science you swap money for deeds to a property , check the obvious legalitys ensure clean titles and stuff etc etc .. a doddle job solicitors pass it to there juniors in the Uk .. and no doubt they do in Spain also ..

One thing i would never ever in a zillion years is buy offplan thats when things get technical , but a proper house with deeds and registered and actually having a roof and 4 walls is easy ..