Once the deal is closed, there should be a formal hand off from DD team to integration teams. This can be achieved by DD read out by the due diligence team on their findings for each functional workstream clearly presenting the assumption or mitigation plan assumed in the business case atleast for the high-risk items. Integration team then need to align their plans as per the mitigation planned.
This can either be by stream or one read out session where all streams participate is preffered in my view as there maybe many cross functional dependencies and knowledge sharing as well.
These meetings can be arranged virtually and can be recorded as well, to help bring any new member joining the integration team up to speed with the deal specifics.
I agree with the points made above, the handover is extremely important as in many cases DD team is separate from Integration team.