replace a failed bigip dns appliance with RMA

We have two bigip DNS systems in a dns sync group, they are both standalone. Due to a hardware issue we have to RMA one of the boxes. Should I restore the RMA unit with a UCS file, then run gtm_add to add the rma unit into the dns sync group? Or should I just manually copy over the bigip.conf, bigip_gtm.conf, bigip_base.conf? Should I not copy any config and just use gtm_add to sync the config from a curent member of the sync group? Also, does bigip_add need to be ran on all of the GTM's that connect to these DNS devices to copy over the certs?

Thanks,