Merge Realm Roles

We have multiple Realm roles created for our data domains in the below fashion

• Data Domain 1
  • Realm Role - Data Owner
  • Realm Role - Data Steward
• Data Domain 2
  • Realm Role - Data Owner
  • Realm Role - Data Steward

How can I merge Data Domain 1 and Data Domain 2 into one single New Domain and merge the corresponding Realm Roles?

I.e.

• Data Domain 1
  • Realm Role - Data Owner
  • Realm Role - Data Steward                                            = New Data Domain
• Data Domain 2                                                                                           New Realm Role - Data Owner
  • Realm Role - Data Owner                                                              New Realm Role - Data Steward
  • Realm Role - Data Steward