Thanks to all for your wise advices and dedication. I've properly finished the project, using an unidimensional array with three elements.
Afterwards, to emulate the switch command of C, a chain of If-else has been made to allow control over the different sprites that make part of the light beam.
Buttons are active and not only change the visibility of the sprites, they change also the values of that array.
As it seems that Construct2 does not allow to pick up more than one instance in a condition, this is the way that solved the issue...(Among a handful of other ways, of course.)
And thanks of the help from the people of the forum!