This Cisco Virtual Lab simulation is OSPF with virtual links for two separate OSPF area 0s. If you had two companies merge with separate OSPF configurations. This created a virtual link in area 1 between iosv-3 and iosv-4 to combine them. I did it for both IPv4 and IPv6. Only changes are in iosv-3 and iosv-4 routing sections. I do show the sh ip ospf virtual-link outputs.
It has before and after outputs for each router. You can see the sh ip ospf x databases for each router before and after the virtual links.