Visualize two halves of the vertical line with different width

[yupenghe]

I am trying to find a way to highlight a path between two nodes in a tree by drawing the branches on the path in a different style (i.e., different colors or different widths). However, when I did that through changing the node style of the nodes on the path, both the relevant half and the irrelevant half of the vertical line will be impacted. I only want to highlight the relevant part.

For example, a tree has three nodes A, B and C where B and C are children of A. When I tried to highlight the path from A to B, the vertical line on the side of C will also be highlighted. Is there a way to highlight only half of the vertical line that is on the path from A to B? Thanks.