When subgraph expands, parent subgraph doesn't change layout

I have nested subgraphs that each use the Parallel layout (Have also tried TreeLayout with the same result). Here is my starting state:

When I click on the innermost subgraph to expand it, this is the layout result:

As you can see, the .switch3_Merge node does not move, leaving to a wonky layout. In an ideal world, the layout after I expand the subgraph would look like this:

Here is the code for my group layout:

return (go.Group, "Auto", { // define the group's internal layout layout: (ParallelLayout,
{
layerSpacing: 75,
nodeSpacing: 10,
angle: 90
}),
toolTip: nodeToolTip,

        // the group begins unexpanded;
        // upon expansion, a Diagram Listener will generate contents for the group
        isSubGraphExpanded: false,

What can I do to get the desired behavior? I was thinking I could always “pin” the merge node to the bottom of the group, but it seems to be an inelegant soluion even if I can figure out how to do that.

Thanks!

Your group template is messed up. Format code in the forum by putting a line consisting of only three backquotes before and after your code.

TreeLayout cannot do what you want.
I’m surprised ParallelLayout didn’t work for you.
Try using LayeredDigraphLayout.

I modified the Parallel.html sample to have a nested subgroup, and had the same layout issue. However, as you suggested, LayeredDigraphLayout worked perfectly! Thanks so much!!