Information about a VBAP, VBAK field...

Hello Experts-

I am working with a scenario where customer orders (sales transaction) are generated in a mySAP CRM 4.0 SP 3 system and are replicated to SAP R/3 Enterprise as sales orders.

Are any of you aware of a field in VBAK and/or VBAP in R/3 that keeps track of the document identifier from the CRM system?

Ideally, I need to be able to reconcile, at the line level, what object an entry in VBAP corresponds to an object identifier from the CRM system.

If not, it will be helpful, at the header level, to know which entry in VBAK corresponds to an object identifier from the CRM system.

I would appreciate your help.

Thank you,

- Vik.