Was B purchased in 2021, or has its activity already been reflected on prior tax returns, combined with A?
If it's the latter, ping the tax firm and see if they have additional guidance.
Using Notes receivable as a set of clearing accounts isn't a bad way to go, that's typically a pretty quiet part of the COA, and keeps it out of A's P&L. If any cash amounts remain in Co A's bank account that belong to B, those should be transferred over. Not seeing admin expenses yet in Notes receivable... that gets into the question of whether B benefited from the admin/office services of A, and how to value that at the spinoff. Travel? Maybe skim the travel accounts using the Transaction detail, look for airfare or lodging related to a visit to a prospective property. Was there financing or insurance required for B's property purchases? No need to reply, just some things that come to mind.
As for moving the data, have seen the Transaction Pro app mentioned often, and just checked, it will import JEs (and other transactions). You've already got the hard part done, because you used those NR accounts to stash expense categories.
