As most will probably know, in Spain insurance policies normally cover any driver, although they do not cover an insured person to drive any other vehicle of the same type, as in UK.
I have just discovered that Linea Directa motorcycle Insurance only ever cover the insured person (owner) to drive the vehicle, and one cannot add any other driver.
There are companies in Spain who will cover other drivers so if you need motorcycle insurance and there is any possibility that at any time you may need another person to drive, do not insurance with Línea Directa.