After you have classified your company data, you should move on to designing your protection groups.
By now you should know which services and data are critical, and classify them into the groups: platinum, gold, silver and bronze.
One thing that is very important is the name standard of your protection groups. It should reflect the company classification of the RTO, RPO, and RLO.
If you have a protection group with an RTO of 4 hours, RPO of 1 hour, and a synchronization frequency of 15 minutes, the name for that protection group should be "RTO 4 hours / RPO 1 hour / Sync 15 min".
This means that the members of that group must be up and running within 4 hours, a recovery point should be created every hour, and between those points, the block-level changes are synchronized every 15 minutes.
It doesn't matter if you mix different kinds of data sources within the protection group. Bear in mind though that a data source can only be associated with one protection...