Hello,
Is there a cable between router 1 and router 2 ?
If yes you have to convert router 2 into an AP.
If the router has an AP mode very good ( you will probably have to move the cable from router 1 into a LAN port but it depends on the make of the router).
If router 2 has no AP mode you will have to :
- disable DHCP on it
- move cable from router 1 in a LAN port on router 2
- give router 2 an static IP from the same subnet as the one from DHCP in router 1
On the Wifi part you could set sams SSID and password on both routers and the devices will move from one network to another if they loose connection or you could just reassign manually.