Final answer:
Sarah can accomplish this by registering BBD Realty, Inc. as a branch office of XYZ Realty, Inc.
Step-by-step explanation:
Sarah can accomplish this by registering BBD Realty, Inc. as a branch office of XYZ Realty, Inc. This allows her to be the only broker for both corporations without changing their names or combining them. By registering BBD Realty, Inc. as a branch office, Sarah maintains separate identities for both corporations while still being able to operate as the sole broker for both.