Run trigger using "run trigger" function

I'm making a trigger (A) in which I need to run another trigger (B) at some time. So I tried to use the function "run trigger", but I can only choose between "this trigger" and a trigger variable. So I tried to set a variable (V) using another trigger so that V would be equal to the trigger B I wanted to run, but I can not set an initial value for trigger variables, and when I want to set V to be equal to B using "set variable", I can again only choose between "this trigger" and another already existing variable. What can I do ? Are trigger variable useless ? How can I define such a variable ?
Please help

All the triggers are listed in the "variable" drop down menu.

thanx lol, I don't know how I can have missed it (actually, I'm using so many variables that I didn't notice the triggers). Thanks a lot for help.