Code

private void Button_Click_1(object sender, RoutedEventArgs e)
{
	AddElemWnd dlg = new AddElemWnd();
	if ((bool)dlg.ShowDialog())
	{
		int nInpNum = int.Parse(dlg.textBoxInps.Text);
		int nOutNum = int.Parse(dlg.textBoxOuts.Text);

		ShapeNode node = m_Diagram.Factory.CreateShapeNode(40, 40, 8, 180, Shapes.Rectangle);
		node.AnchorPattern = CreateAnchorPattern(nInpNum, nOutNum);
		node.EnabledHandles = AdjustmentHandles.ResizeTopCenter |
			AdjustmentHandles.ResizeBottomCenter | AdjustmentHandles.Move;
		node.HandlesStyle = HandlesStyle.EasyMove;
		node.Brush = Brushes.Black;
		NodeProperties props = new NodeProperties(nInpNum, nOutNum);
		node.Tag = props;
	}
}

AnchorPattern CreateAnchorPattern(int nInpNum, int nOutNum)
{
	AnchorPointCollection anchorPnts = new AnchorPointCollection();
	double nOffset = 100.0 / (nInpNum + 1);
	for (int i = 0; i < nInpNum; ++i)
	{
		AnchorPoint point = new AnchorPoint(0,
			nOffset * (i + 1), true, false, MarkStyle.Rectangle);
		anchorPnts.Add(point);
	}
	nOffset = 100.0 / (nOutNum + 1);
	for (int i = 0; i < nOutNum; ++i)
	{
		AnchorPoint point = new AnchorPoint(100,
			nOffset * (i + 1), false, true, MarkStyle.Rectangle);
		anchorPnts.Add(point);
	}
	return new AnchorPattern(anchorPnts);
}

void ChangeAnchorPnts(int a_nInps, int a_nOuts)
{
	var node = m_Diagram.ActiveItem as ShapeNode;
	if (node == null || !(node.Tag is NodeProperties))
		return;

	NodeProperties props = (NodeProperties)node.Tag;
	node.AnchorPattern = CreateAnchorPattern(a_nInps, a_nOuts);

	var linksToDelete = new List<DiagramLink>();

	foreach (DiagramLink link in node.IncomingLinks)
	{
		if (link.DestinationAnchor >= a_nInps)
			linksToDelete.Add(link);
		else
			ReassignInLink(link, link.DestinationAnchor);
	}

	foreach (DiagramLink link in node.OutgoingLinks)
	{
		if (link.OriginAnchor - props.IncommingPointCount >= a_nOuts)
			linksToDelete.Add(link);
		else
			ReassignOutLink(link, link.OriginAnchor - (props.IncommingPointCount - a_nInps));
	}

	foreach (DiagramLink link in linksToDelete)
		m_Diagram.Links.Remove(link);

	props.OutgoingPointCount = a_nOuts;
	props.IncommingPointCount = a_nInps;
}

private void ReassignInLink(DiagramLink link, int newIndex)
{
	link.DestinationAnchor = -1;
	link.DestinationAnchor = newIndex;
	link.Route();
}

private void ReassignOutLink(DiagramLink link, int newIndex)
{
	link.OriginAnchor = -1;
	link.OriginAnchor = newIndex;
	link.Route();
}