I use GetGUI()->SetParameterFromGUI but it is not available in IPlug2, unfortunately SendParameterValueFromAPI does not work quite well (sometimes).
NOTE:
Basically I have four different parameters/(gui)controls that are mutually exclusive.
I cannot use a one control for all
radio control, tabs etc) they are of a different type of function, I need among other things that each one can associate with external controllers through the host midi learn process.
Ps:
neither does the IPlug1 method that consisted in assigning a control to a variable, when declaring it.
That method was very simple and useful, it never gave me a problem.