From my experiences we do cross border lead by Headquarter that hire all advisors needed including legal advisors that could be needed in the subsidiaries from many countries.Current subsidiaries should be involved with special limited expertise that will assist the team doing DD for integration plan.
The Financial Fund needed for the transaction in the headquarter there will be Financial team that will have helicopter view to calculate the pro forma for the company including maybe issue bond etc.
For the post integration, the Headquarter will have a strong leadership to execute that involve all subsidiaries or SBU in the company in order to realise the synergy.
