Hi Karthik,
The key function module here is BBP_PD_CONF_TRANSFER_V2 which gets called in a update task during the transfer.
If you go into this FM as below, you'll find where the system separates GR and SES.
FM BBP_PD_CONF_TRANSFER_V2
FM BBP_PROCDOC_TRANSFER
Form procdoc_transfer
Form transfer_grse
CASE i_be_object_type.
...
WHEN c_b_se.
...
WHEN c_b_gr.
Hope this could help you with your query.
Regards,
Wendy