Thanks. I hadn't used that feature before. That solves the "1" and "2" issues.
But I'm still not completely sure about the others.

A - Plan 1
B - Plan 2
C - Plan 1 & 2 combination of both plans at a discount
D - Plan 3

Here's my (hopefully final) dilemma:

Options that need to be possible:

* A, B
* A,D
* A, B, D
* NOT A & C
* B, D
* NOT B & C
* C, D
* D

Basically, I just need to make it so that
1. They can't subscribe to A & C at the same time, or B & C at the same time
2. If they have A and want to purchase C that it 'upgrades' them (add C, remove A, apply balance of A toward C)
3. If they have B and want to purchase C that it 'upgrades' them (add C, remove B, apply balance of B toward C)
4. If they have A and B and want to purchase C that it 'upgrades' them (add C, remove A and B, apply balance of A and B toward C)
5. If they have C they can not purchase A (unless there is a way to 'downgrade' from C to A, and apply balance of C to A)
6. If they have C they can not purchase B (unless there is a way to 'downgrade' from C to B, and apply balance of C to
7. D has no effect on A, B, or C at all (it is completely 'independent' of any A,B,C subscriptions).

Is this possible? I know that I can control access via workflow; however, how can I make the 'upgrades' (applying remaining balances, cancelling previous subscription) work (2,3,4 - and ideally 5, 6)?

Or, possibly more generically, what exactly 'allows' one subscription to be 'upgradeable' to another. Is it setting up as a sub-plan? Or is there some other means?

OK ... finally trying to implement this ... I've reviewed the videos and read the manual and still not exactly sure how to set the workflows settings to make a specific plan/workflow behave as needed.

Based on these plans:

A - Plan 1 -$200
B - Plan 2 - $200
C - Plan 1 & 2 combination of both plans at a discount - $300
D - Plan 3 - $100

How should I configure the workflow for Plan A so that:

* It can be purchased at registration
* It can be purchased any time later (basically, it has no rules regarding when it can be purchased)
* It can be renewed (when it expires)
* It can NOT be purchased if existing subscription to C (which I already know how to handle with the conditions)
HOWEVER
* It should not actually allow 'upgrading' (i.e. change subscription) from D to A. (THIS is what I'm not sure how to ensure)
If they already have D and purchase A that is fine, but if they do, they should continue to have plan D as well as plan A.

I think if you can explain that I'll have a better understanding how to make all the other conditions work.

OK ... I'm still stumped and not able to get this to work as needed.

I think it comes down to me understanding one thing that I didn't see an answer to before ...

what exactly 'allows' one subscription to be 'upgradeable' to another. Is it setting up as a sub-plan? Or is there some other means?

Also ... is there a way to control workflow differently for the first time a user purchases a subscription vs subsequent upgrades (IF they don't purchase any subscriptions when they register)?