I might do a case study on how to split a multi subsidiary company into 2 netsuite instances from 1 instance - move transactions, assets, employees, projects and customizations including scripting. NS professional services said it cannot be done but I was able to do it with a margin of $0.37 difference on $150 million asset split. Even had to split some transaction line items to two new companies. It took me and my partner over 4 months 15+hrs day.

I've seen this done in reverse: A One World instance acquires a non-OW. Data migration for days.