I've managed to do this definition in Simulink, with this script:
sfnew
rt = sfroot
m = rt.find('-isa','Simulink.BlockDiagram')
ch = m.find('-isa','Stateflow.Chart')
sA = Stateflow.State(ch);
sA.Name = 'A';
sA.Position = [50 50 310 200];
sA1 = Stateflow.State(ch);
sA1.Name = 'A1';
sA1.Position = [80 120 90 60];
sA2 = Stateflow.State(ch);
sA2.Name = 'A2';
sA2.Position = [240 120 90 60];
tA1A2 = Stateflow.Transition(ch);
tA1A2.Source = sA1;
tA1A2.Destination = sA2;
tA1A2.SourceOClock = 3;
tA1A2.DestinationOClock = 9;
tA1A2.LabelPosition = [180 140 0 0];
tA1A2.LabelString = 'E1';
pos = tA1A2.LabelPosition;
pos(1) = pos(1)+5;
tA1A2.LabelPosition = pos;
% Add a default transition to state A
dtA = Stateflow.Transition(ch);
dtA.Destination = sA;
dtA.DestinationOClock = 0;
xsource = sA.Position(1)+sA.Position(3)/2;
ysource = sA.Position(2)-30;
dtA.SourceEndPoint = [xsource ysource];
dtA.MidPoint = [xsource ysource+15];
% Add a default transition to state A1
dtA1 = Stateflow.Transition(ch);
dtA1.Destination = sA1;
dtA1.DestinationOClock = 0;
xsource = sA1.Position(1)+sA1.Position(3)/2;
ysource = sA1.Position(2)-30;
dtA1.SourceEndPoint = [xsource ysource];
dtA1.MidPoint = [xsource ysource+15];
sfsave(m.Name, 'myModel');
It's this behavior that I want to know if LabVIEW supports.