Will Changing the Company Number on Business Units update all historical transactions?

We are going to be consolidating Company 2 into Company 1 and using DocId 626863.1, Changing the Company Number on Business Units and Accounts, as a guide. Will all past history be revised such that any supporting transactions for auditing of Company 2 will no longer exist? And because the Close Year Program, P098201, will be run as a post update task, will all of the retained earnings for Company 1 now be restated to include Company 2?  The document also indicates that Sub Ledger transactions such as A/R (F0311) and A/P (F0411 and F0414) will not need to be