@James94Hodges: as a result of your tutorial I´ve been playing with sliders in umg and works just greaT 
However I was wondering whether it would be possible to have one slider to control all actors (or a certain group of actors) in the level
sort of “one slider to rule them all” 
kind of thing. Why?
1 - I´d like to have a main menu where I could control that sort of option…say …let´s inscrease the amount of wetness in a material in all actors that use it.
2 - Let´s say the one has a road made out of several segments/parts, it would be a bit unpractical to have widgets on each and every one of them, so you ´ve to slide each and every one as you went down that road.
So in UMG could you please explain how to have 1 slider anchored to a certain spot that controls more that one actor or scalar param materials?
Thanks