Share registers and certificates, the corporate charts, resolutions authorising the transfer, amended constitutional documents, registry filings in each jurisdiction, and any employer letters naming a legal entity. Also refresh evidence of continuing international business activity, since a consolidation can change which entity trades.
Version-control the packet
Give every document in the file a version and a date, and keep a single list showing which items assume the old structure. When completion happens, that list becomes the refresh task. Letters are the usual casualty: an employment letter naming a company that has since been absorbed reads as an error even when the underlying employment is unbroken.
Reissue them on the correct entity's letterhead rather than annotating the old ones. Order the refresh by lead time rather than by importance. Registry extracts from a foreign jurisdiction, certified translations and apostilles take the longest and can be requested as soon as completion is confirmed.
Internal documents such as charts, letters and resolutions can be produced in days once someone with authority signs them off. Working in that order means the slow items are already moving while the fast ones are drafted. Keep the superseded versions rather than destroying them, since the transition between the two structures is itself part of the story the file has to tell.