sharing data between two gui's

I basically have one main GUI that is calling for a smaller GUI which simply contains a table and a push button. What I want to do is be able to obtain the data that the user inputted into the table in the smaller GUI and put it in a table in the main GUI; all done by using the pushbutton in the smaller GUI. Here is the following code I tried but failed:

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MasterSet.m is the smaller GUI

ACModel is the main GUI =====================================================================

In the OpeningFcn function of the main GUI:

guidata(hObject, handles);

setappdata(0, 'hMainGui', get(handles.uitable12, 'Data'));

setappdata(get(handles.uitable12, 'Data'), 'NewValue', handles.MasterSet);

In the Re-Apply button of the smaller GUI:

guidata(hObject, handles);

setappdata(0, 'hMainGui', get(handles.uitable12, 'Data'));

setappdata(get(handles.uitable12, 'Data'), 'NewValue', handles.MasterSet);