How can I turn on the show multiplicity option to association shape and access 4 position in visio using c# and Microsoft.Office.Interop.Visio.
The User.ShowMulti
cell in the Association shape's ShapeSheet controls the multiplicity option. You can set it thought Visio's API like this:
shape.get_Cells("User.ShowMulti").Formula = "TRUE"
The 4 access positions are sub-shapes in the association shape. The order in the Shapes collection should be fixed so you can do something like this:
shape.Shapes[1].Text = "Top Left";
shape.Shapes[2].Text = "Bottom Left";
shape.Shapes[3].Text = "Top Right";
shape.Shapes[4].Text = "Bottom Right";