Making a leaflet visualization, using 2 shapefiles

Dear all,

Here is what I want to do. I have regions in a country and subregions
within those regions. I need to make a leaflet visualization so that when I
hover over a point in the map, 2 things should happen :

1. The entire region boundary should be highlighted.
2. The tooltip should show the name of the subregion and the region.

I have 2 shapefiles,one for region and one for subregion. I can use one at
a time but requirements need inputs from both the shapefiles.

I asked this query,along with a minimal working example here :

https://stackoverflow.com/questions/48924514/using-data-from-2-shapefiles-with-leaflet-in-r?noredirect=1#comment84855712_48924514

I did not receive any replies  so I am asking this query once again here.

Best Regards,
Ashim.