If they are individual host, that is the only Option you have to add each host to Object Group. if you add network other device in the network get blocked. so personally i only see that option.
From my notes difference between host and network.
- object just contains a single type of object, whether it's network object (single IP address or subnet), or service object (tcp port(s), protocol, udp port(s)).
- object group contains a group of objects, so you can combine all the same type of objects into a group, eg: a single IP, subnets, different subnets, different IP into one network object-group.