Source Lines in Oracle Assets EBS R12.1.3

1. System is not allowing to enter supplier name in an already available source line of an asset. Can we enter or update the Supplier's name in an already present source line of an asset?
2. Can we add manual source lines in an asset for information and reporting purposes? Is there any financial impact if we add manual source lines in an already created asset routed from AP or uploaded through WEBADI?
3. System is not allowing to delete a manually added source line from an asset? How can we delete a manually added source line from an asset?
4. Is it safe if we manually add multiple source lines in an asset for information and reporting purposes?