Company A and Company B are unvder the same ownership (A Group)Company A and B are both running Nav version 4.0 or later.
You can get yourself up to speed on the standard Nav IC posting features. You can use the Intercompany posting routines in Nav to exchange Sales orders & Purchase orders between companies without re-keying.
In the chart of accounts you will need to setup Nav posting groups to map your intercompany movements to defined g/l accounts.
e.g. Sales - Intercompany (P&L).Purchases - Intercompany (P&L).
Debtors Control - Intercompany (Balance Sheet).
Creditors Control - Intercompany (Balance Sheet).
These stand as normal accounts in the chart of accounts and are presented as normal in management accounts in Company A or B but need to be isolated just for the purposes of consolidating A & B into the Group accounts.