When we configure EIGRP on interfaces that are not on the same subnet we will get a message from EIGRP telling us this. What happens if we configure EIGRP on secondary interfaces? Try this setup with two routers:
Primary IP: 18.104.22.168/24
Secondary IP: 22.214.171.124/24
Primary IP: 126.96.36.199/24
Secondary IP: 188.8.131.52/24
Then you enable EIGRP and run network 184.108.40.206 0.0.0.0 and 220.127.116.11 0.0.0.0 respectively on each router. Will they be able to form an adjacency? Post your answer in the comments section.