Inter company transactions

Hi to ALL,

I want to pass an inter conmpany transaction. The scenario is as follows.

Company code 2 is the customer for company code 1. Company code 1 will bill the Co code 2 and then they will receive the payment.

What are the GL accounts which I need to assign in T- code OBYA. Also from which T- code I can [pass this transactions.

Also If I assign a cost centre /profit centre of One co code it says this profit centre does not exists in second co code.

How this problem can be solved?

Pls tell me solution very urgently.

Thanks

Tanuja