Hi Tamil,
1. The changes will affect the SC line items.
For example, if you delete one item from PO, and if the PO was created from SC directly (without going to sourcing cockpit), this corresponding SC item will get status I1115 - Follow-on Document Deleted.
The SC status is updated by report BBP_GET_STATUS_2.
2. Are you transferring SC to backend via XML? If so, you need to check both the inbound and outbound XML. You may refer to note 1270081 to do some trouble shooting of SOA services.
If you are transferring SC to backend via traditional RFC, you may check in RZ20 for error logs.
Anyway, to ensure you are able to transfer again the SC succesfully, firstly you need to find out what error has happened and fix it. After that, you may re-transfer the SC with this report BBP_SC_AUTO_RETRANSFER. You'd better implement note 1788671 to add Shopping Cart as a parameter so that you could retransfer a specific SC.
Hope this helps you.
Regards,
Wendy