Input parameter in binding widget component

I have something look like skill tree. By clicking on button I need to add points and change brush for button. I wanna to use only one function to bind it in every button I need. So this function need to know about in which skill I change something. How may I set input parameter in binding function?
Just adding input NewParam in function make an error “Error Binding: Property ’ BrushDelegate ’ on Widget ’ ImageSkill1 ': Member:GetBrushSkill1 Has the wrong number of arguments, it needs to return 1 value and take no parameters.”
So I need to make something like in Construction Script for bp, but for widget binding function.
Thanks in advance.