You can have nodes in cells with different capabilities. Currently, this means having a cell with nodes on both distributed platforms and z/OS nodes. In the future, there might be other situations that fit this criteria. However, there are still restrictions on how the nodes can coexist. For example, you cannot have mixed nodes in a cluster. Node groups are created to group nodes of similar capability together to allow validation during system administration processes.
A default node group called DefaultNodeGroup is automatically created for you when the deployment manager is created, based on the deployment manager platform. New nodes on similar platforms are automatically added to the default group. A node must belong to at least one node group, but can belong to more than one.
As long as you have nodes in a cell with similar platforms, you do not need to do anything with node groups. New nodes are automatically added to the node group. However, before adding a node on a platform that does not have the same capabilities as the deployment manager platform, you will need to create the new node group.