Thank you @Ermin Trevisan,

You refer that companies can be "hierarchically consolidaded" and perhaps this can solve my problem.

The tests I have made where on core Odoo modules with no custom module installed and with 2 companies. The main company and the child company. After basic setup with some invoices on each company,  i have noticed that entries from child company are not shown on main company. Perhaps and as you refer, i might have some access rules issue.

Our reality is very specific and every detail from each "branch" is a must... for instance, even if the same company have two stores, on the same city, each store must have it's own sequence (for all documents), each address have to be shown on issued documents, different taxes based on geographic location and so on... it's really a headache to setup a systen as such conditions (users moving from a branch to another, different taxes for different areas, same partner selling/purchasing from/to different areas... and dependending on company class... each government responsability have to be taken care on each geographic location). Basically it's the same company with different rules...

My idea was to use the "multicompany" environment functionalities (with some tune-ups) in order to achieve what we need without having to write a module for that. 

So, when you say "hierarchically consolidaded", you mean that core modules allows me to have all accounting entries from all child companies controlled from a single master company? If so, my problem is solved and I will "fight" until I find it o:).

Basically, multicompany will help me if I can get a way to have all child companies entries controlled by a single main company.

Thank you very much

Best regards

PM