Right way to save settings of vector of ofParameter in a ofxguiGroup / ofxGuiGroupExtended

when you resize a vector like that it'll create 1 element and then copy it to all positions. Since ofParameter has shallow copy semantics a copy of a parameter is realy a reference to it not a full copy so when you call set on the different positions of the vector you are changeing that 1 parameter you have created and for which there's several references in the vector. to avoid it you can use push_back instead of resize but i would advice you to use ofParameterGroup instead and then just setup the gui group with it like:

//.h
ofxGuiGroup MaskWindow;
ofParameterGroup MaskParameters;

//.cpp
...
for (int i = 0; i < _nFam; i++)
{
    string fam = "Family " + i;
    ofParameter<bool> param("Blend", false);
    MaskParameters.add(p_blend);

    ofParameter<bool> param("Alpha", 255, 0, 255);
    MaskParameters.add(p_alpha);
}
MaskWindow.setup(MaskParameters);

you can also have separate parameter groups if you prefer to have them separated by type and then add the parameter groups to the ofxGuiGroup or directly to an ofxPanel...