Looking for adding existing switches to sonoff with LED status showing state

Would really appreciate if someone could point me to this.
Want to be able to use existing switches with sonoff such that manual triggering updates status online as well.
Also want to add a led status light to the manual switch as well.

Thanks in anticipation!

When using Sonoff in combination with MQTT you automatically have this. The switch sends a stat message when locally operated. The led function is controllable via de console at the webinterface of the device. For details see https://github.com/arendst/Sonoff-Tasmota/wiki/Commands

Thanks a lot for the reply.
I am looking for how to connect Sonoff to external switch and external LED in a switch.
I am looking for a hardware tutorial.
Thanks again.

Sorry to have misread your question. Adding a physical extra switch is possible but I would not use any mains powered Sonoff for this because of safety. If you would get a short of your switch or LED to safety earth your Sonoff will blowup.

The Sonoff SV is a good option and you can use the existing headers J6,7

The pinning of this headers is in the schematic: https://www.itead.cc/wiki/images/0/09/Sonoff_SV-Schematic.pdf

You can see they are connected to GPIO4 and GPIO5
In the configuration of the sonoff you can connect these to and input and a output. Do not forget to add a resister if you wire a LED to the output since it will drive at 3v3. Assuming ~2mA is enough for your LED this resistor must be 470 ohm
For the input you need can select switch1 in the Tasmota configuration which will outomatically aslo drive your relay.
If you do not want this you need to disconnect them via commands in teh console. Details are given here: https://github.com/arendst/Sonoff-Tasmota/wiki/Understanding-SwitchMode-and-SwitchTopic.

Good-luck!