RE: Resources or Best Practices for Merging Two NetSuite Instances
I’ll possibly be merging two NetSuite instances and am looking for any type of documentation about this process. Or, if you’ve gone through this process yourself, any tips or tricks you might have would be appreciated. Still a lot of unknowns, but I want to prepare just in case.
Bundling is going to be your best friend. The less you manually do the better.
I would generally disagree with this answer – bundles are likely to create issues unless targeted very specifically. I’ve been burned once or twice and generally don’t touch that feature if I can avoid it.
The copy to account functionality is promising – but it’s still needing some additional development, as you have to make sure all your dependencies are copied over manually at this point.

I agree with Kevin, I have migrated quite a few instances, segregate companies (see blow) and new implementation – bundling can cause severe problems by adding multiple copies of custom fields, list etc due to reference linkage . It also changes the forms too. Bundles can bring in lot of unnecessary artifacts.