I would really appreciate a bit of guidance on the suggested approach to accomplishing my goal. It seems like it should be easy, but I run into a problem no matter what I do.

I want to have two basic plans for the user to choose from.

The first plan is basically a trial. It last for two months and costs 10 dollars.

The second plan is a "full" subscription. It lasts for one year and costs 20 dollars.

I want the user to be able to upgrade from their trial membership to a full membership by paying the 10 dollar difference. Here are the problems I am having...

1. If I make the two plans as exclusive top level plans I get the initial registration correct. However, when a user goes to upgrade their trial membership the Full membership is being billed at full price (20 dollars) instead of the discounted price (since they already paid the first 10 dollars to get the trial.)

2. If I make a third plan, which is basically a duplicate of the Full plan and set it as a child of the Trial plan I am able to set the new plan as only costing 10 dollars and can upgrade just fine. However, then the user's subscriptions list two plans (the trial, and then below that the full). These subscriptions will both then deactivate after the first two months when the parent Trial plan expires, despite the child plan having a 1-year period. I don't suppose there's a way for the child plan to override/overwrite its parents, huh?

3. If I make a third plan, which is basically a duplicate of the Full plan and set it as an exclusive top-level plan that is an upgrade only I get the correct behavior on registration and trial upgrade. However, if the user selects to buy the Full membership from the beginning they are still presented with the "upgrade" to what looks like, and basically is, the plan that they already bought.

Is there a way to display a plan as an upgrade for one plan, but not for another? I thought that might be a possible use for child plans, but apparently not.

I have no idea what the recommended approach is here. The documentation hints that this can be solved by using the "Pricing and Validity" settings for my Full plan but it offers no details whatsoever. I have messed with those settings quite a lot and nothing I do there seems to be at all useful. All that section seems to be good for is setting separate prices for recurring payments, which I am not using.

Pretty please can somebody point me in the right direction? This is really, really frustrating. This seems like incredibly basic behavior, but I can't seem to find a workable combination of plans.

Thanks in advance.
~ Jason