You may need to add another unit to a subscription in certain scenarios. i.e. if you are giving a customer 2 x 50 sq ft units to make up a 100 sq ft unit.

Visit the Subscription and select Add Unit.

You will then select the next unit and Save Allocation to save your changes.

Allocating more Units does not update the subscription price. You can learn how to add an additional Unit Type to a Subscription here.