Related to Contract, Subscription , Amendements and Renewals.

We are planning to use Salesforce CPQ (for Quoting process) and NetSuite (for Contract Renewal Process). As a result subscription records won't be created by CPQ as the contract creation will sit with NetSuite.

Salesforce CPQ does not do amendments or renewals correctly if subscription records are not created on the contract.

Because of the above design we have to try and find a way to create subscriptions records manually  when the contract creation is trigerred by Netsuite into Salesforce

Question 

1) Has anyone tried creating subscriptions using custom logic or tricked CPQ logic into creating subscription records on an already created contract?

2) On renewal the existing contract subscriptions records are updated with renewal information which is then carried forward to the renewal Opportunity line items and Quote - Quote Line item , which  due to the design change has to be done using custom code 

Any suggestion or ideas on the above?

Thanks