How to relay message from one node to other in mesh network


I have 3 of nRF52840 boards, SDK V2.2.0 and nRF SDK V15.0.0.

I already tested the light switch control example, and saw it working with one client and 2 servers and all the 2 servers within the client's range.

Now my question is,

1) How can i relay the message to node not in range?

2) For relay what changes are needed in code?

3) Can i use nRF mesh app to control set/reset?