execute ddl command on protected realm schema

Hi,

I need your support.

I am designing security model where DBA user can perform DDL command on protected vault realm schema ,

user_dba has dba role

app_user is the owner of application objects and protected by realm app_realm.

objective : user_dba wants to perform ddl on app_user schema ( like create table / rebuild indexes ….)

I do not want to give user_dba the relam authorization either owner or participate.

How can I implement this model ? ( i tested command rule but not work because user_dba not has auth on realm).

thanks