Backcharging companies which are in the same controlling area using WBS

I have an Investment project in company 'A', it has a budget of $ 900,000 $ and they are making an asset, the expenses of which will be partly shared by company B and Company C. For, eg, consider I have actual expenses of $ 900,000 on this project, I want to backcharge company 'B' and company 'C' with $ 300,000 each. Now, company 'B' and 'C' will also have projects to capture the backcharges from company A and these project will have budgets($ 300,000 each).

Overall, if I look at my total budget for all companies put together it will be 900,000(company A) + 300,000(company B) + 300,000(company C) = $ 1.5 Million. This is incorrect because budget for this project should have been only $ 900,000. How are these projects handled.