Relation Between Shopping cart and RFX

Hi Experts,

    I have a requirement where if we provide the Shopping cart number then it should fetch me shopping cart details and RFX details(if RfX is created as follow-on document).

I tried to relate using tables CRMD_ORDERADM_H and CRMD_ORDERADM_I tables but did not found link between these two.Even I tried BBP_PD transaction but i am unable to figure out the relation.

Please suggest me some tables or function modules through which i can fetch the RFX details based on shopping cart number or GUID.

Thanks & Regards

Aishwarya.M