This blog post will provide a high-level overview of the steps required for adding a new F5 BIG-IP device to an existing device group and syncing the group configuration to the new device. The steps listed below assume each BIG-IP device is of the same series and model, running the same software version, and therefore fully compatible.
It is possible to add a device of a different series and/or model to the device group and sync the configuration between them. However, if you use the embedded HSM to store your digital certificates and keys, the new BIG-IP device must be of the same series as the current device to sync that information. Otherwise, you will have to add your certificates and keys manually to the new device upon initial configuration, and each time you renew or add new certificates and/or keys. Therefore, any attempt to deploy such a configuration may not be possible and is not advisable.