Another home automation idea, but with feedback

I want to make a bunch of modules that i can fit to the back of wall switches so that I can choose to switch them using an arduino. I want to still be able to control the lihght at the wall manually too. The attached picture shows a schematic of an hall effect current sensor a relay module and the wall switch. I’ve found a couple of nice break out boards to do what I need. I was also thinking of daisy chaining 3 together with RJ45 sockets. Any thoughts?