How to get context-sensitive syntax coloring for the same keyword in Vim?

I am creating a vim syntax file for a niche language that does not yet have a syntax file. When setting up a simple function, the language has the following syntax.

foo(parameter)
    if parameter then
       print("yes")
    else
       print("no")
    end
 end

I want the end to be conjugated with if in order to have syntax coloring for conditional expressions, and the “end” paired with the function declaration has a functional syntax coloring. How do I achieve this? I am currently completing a keyword. This ensures that it is colored, but it matches the color only if, but not the name of the function.

Thanks for any help.