Renew multiple subscriptions into 1 forecasted renewal

We need the ability to roll-up more than one separate active subscription into 1 forecasted renewal. For example, a customer has 3 different product contracts each with a different contact start and end date. We are bundling all 3 products plus adding one new product into 1 renewal agreement which should be represented by one active subscription line. We need a way to link/roll-up all 3 individual active subscriptions into the 1 new active subscription.

The amendment functionality is not a viable solution for this situation.