Well, yes and no.
LayeredDigraphLayout is designed to re-order the nodes in each layer to reduce the number of link crossings. There isn’t a property that you can set to avoid that.
It is possible to do so by overriding some of the methods to avoid doing any crossing optimizations.
But even if you do so, there’s still no guarantee that a particular node will be positioned with the same X value as another node.
Are you sure that you can’t use TreeLayout? TreeLayout does support ordering of tree children.
I don’t recall off-hand what to override, but I would start with making ReduceCrossings a no-op.