What is a sister entity?

Could you please elaborate on the concept of a "sister entity"? How does it differ from other types of business relationships or associations? What are the potential benefits and drawbacks of having a sister entity? How does it impact the overall corporate structure and operations? Is there a specific legal framework or requirements that need to be met for an entity to be considered a sister entity? Can you provide any examples of successful or notable sister entities in the cryptocurrency or finance industry?