I want to sell two membership options. Currently, I can't prevent someone from adding both to the cart and purchasing them at the same time.

Of course, It's unlikely a user will do that, but why not allow for that setting.

I'm sure there may be other scenarios where you might want a user to purchase either one product or another. (especially ones that move users to a new member group)

 

If I would wanted to set this up, I would do this through primary groups. The purchase of “membership A” moves the person to “primary group A” and the purchase of “membership B” moves the person to “primary group B”. The “membership A” product is set to be not available to group B and the “membership B” product is set to not be available for group A. 

 

If I would wanted to set this up, I would do this through primary groups. The purchase of “membership A” moves the person to “primary group A” and the purchase of “membership B” moves the person to “primary group B”. The “membership A” product is set to be not available to group B and the “membership B” product is set to not be available for group A. 

That wouldn't stop them from buying two memberships because at the time they wouldn't be either A or B so both would be available and therefore both could be purchased at the same time.

Similar, when having a product tree/tiered system (A->B->C->D) and using the upselling feature, adding a higher tiered product doesn't remove the lower tier from the cart. Unless I'm just configuring it wrong... :\

I am a little new to e-commerce side of things.