Like everything you have to do it legally, remember this is not a simple thing.

Are you are uk company or spanish company?
Your staff will be spanish registered, so which employment system would you use?

Speak to Dr Crespo on the other email address. Remember he is a lawyer, he is good, but his time is not free. In 5 minutes he will give you the answer.- probably.

Dr Crespo & Partners - International Lawyers, SRL