intercompany sales

hi all,

In intercompany sales, suppose the ordering company code is 1000 delivering company code is 2000. then 1000 invoices the customer and then intercompany invoice is to be created.

Then my question is

-wrt which document the ordering company creates the customer invoice? if it is delivery document created by 2000, then how 1000 has access to delivery document created by 2000?

-2000 will invoice 1000 by intercompany invoice which will be created wrt cust invoice. then how does 2000 has access to cust. invoice created by 1000?

and if this 'access' is thru SAP, what copy cotl settings are needed?( i know all basic configuration of intercompany sales. the doubt is this 'access' part)

hope u get me right n mispell my confusion. thx