Intercompany transaction in Purchasing

We have vendor in company code A. We will create a srevice related PO in company code A. Invoice received should be in company code A. The payment will be done in company code A. The actual service is done for company code B. Therefore, the expense account in company code B instead of company code A should be debit. This is basically an intercompany related transaction. Are there anyone who can hlep me to show me how I should configure SAP in MM for intercompany related transaction?

I did the inter-company configuration by using GL account in OBYA. However, I can do the intercompany posting in FI side. I could not do the intercompany posting for the transaction code MIRO.

I greatly appreciate it if somebody can give me light.

Thank you.

Frank