I have a serious challenge in determining the best approach to this issue.

A group called T has 3 sub groups called I,S,H respectively and they are into 3 different types of business.(advertising,security and digital board sales).

Sub group I has 6 unit companies under it who do similar jobs but specialize in different aspect of advertising

Sub group S has 3 unit companies under it 

Sub group H has 7 companies under it.

Now is it best to have one single chart of account for all the companies ?if yes how do we ensure control of not allowing the expected reports in this companies not to be overwhlemed with ledgers not useful to their business.

or do we setup individual chart of accounts for each company ?if yes how do we get consolidated reports per sub group and above all at the Group T.

This is giving us sleepless night and hence we have not been able to generate effective results. Please who has done this successfully and how?