Hi Bhavik,
If I understand your concern correctly, if 1 Quote with multiple line items is present then 1 single service agreement should be created with all line items. Each product instance can have its own terms and conditions.
For point#2, ideally a new product shouldn't be added to an existing agreement unless it is an associated product or a VAS offering. Addition of a sub-product (like VAS) if added should result in new contract version.
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Rupen Dewan
Tata Consultancy Services
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