In the customer details page, we can list up to 20 subscriptions for now. In case you have more that 20 subscriptions under a customer, the list cannot be viewed in the customer details page.

To get a list of all subscriptions under a particular customer, you can visit the Subscriptions tab and use the Show Filter option to list the available filters.

 From here, you can use the Customer's information to filter the subscriptions and see all the subscriptions under a particular customer/reseller. 

Note: On the recent UI enhancement you can now scroll the index pages - Customers, Subscriptions, Invoices, and Credit Notes vertically. Earlier, the pages will be paginated which may prolong your search however with the new enhancement as you scroll down the list it will load all other data in a single page as highlighted below on the screenshot. Refer to this link for more information. 

 

Additional info:

If you are implementing reseller type business model, generally, we recommend the usage of addons due to the significant number of subscriptions that a single customer {reseller} can have. 

For example, if the reseller purchases an initial subscription, and wants to add more subscriptions later, you could configure recurring addons which they could include to their existing subscription via the customer portal. You could also use "Update Subscription" API to attach these addons to the customer's current subscription.

This way, the customer/subscription record would be created only once in Chargebee, but they can have multiple purchases tagged under it as each of the invoice {with addon item} would refer to an additional subscription purchase.

The above flow would work only when your requirement is only to have a flexible filtered view of the customer's purchases.

However, if you'd want collect the appropriate amount from the customers whenever they make a purchase, the suggested flow would not be the right fit as the concept of "proration" would come in to influence during this process. For example, if customer purchase the initial subscription on July 15th, and later add more addons {say $15 each} to the subscription on July 25th, the addon amount with deducted prorated charges would only be collected immediately {the 10 day period between July 15th to 25th would be taken into account as subscription's usage and the respective amount would be deducted from the addon charge}.

Otherwise, you could deselect proration, but this would make the full addon amount to be collected only on subscription's next renewal date.