How can I join 3D points on an "axis object" by brushed sweep?

I have the following problem. I have a Gui that contains a 3D "Axes object". I have a few points in the "axes", and what I want is that through "brushed" I can join 2 selected points.

At the moment I only have this cogigo that only allows me to obtain the "Data" property of the last point inserted in the "axes", but I require the data of 2 selected points and the possibility of joining them. Thank you very much for your help.

function Button_unir_Callback(hObject, eventdata, handles)
% hObject    handle to Button_unir (see GCBO)
% eventdata  reserved - to be defined in a future version of MATLAB
% handles    structure with handles and user data (see GUIDATA)
brush on
brushed_locs = get (handles.Grafic, 'Data' );
set(handles.text4, 'String', brushed_locs );