I have created a few subscription plans for my forum as shown below. If you see the list, you will notice that members can buy an upgrade for 1 month, 2 months, 3 months and so on. Let's say if someone buys a one month plan and half way through he buys a two months plan. How do I set the plans in such a way that the 2 months plan gets added on to the existing one month plan? My current set up gets a new purchase to cancel any older purchases. Need some help here please. Thanks.