Need help to structure plan for upgrade

I need urgent help to structure/set up plans for upgrade. Right now I have 2 plans:

1. Associate - $45/year
2. Full - $55/year

Associate member needs to be able to upgrade to Full plan anytime during their subscription and only pay the difference ($10 regardless when they upgrade, not pro-rated).

I found this thread - www.joomlapolis.com/forum/88-usage/120339-how-to-have-an-upgrade-plan-not-show and structure the plans as follows:

Plan 1 - Associate - $45/year, exclusive, no upgrade, no prorate
[Child] Plan 2 - Upgrade to Full - $10/year, non exclusive, upgrade, no prorate
Plan 3 - Full - $55/year, exclusive, upgrade, no prorate

Following the plan structure means member who sign up for Plan 1 and then later Plan 2 needs to renew both plans each year instead of being assigned Plan 3. This is not practical and won't make sense from member's point of view.

Is there any other way to configure the plans?

Associate member needs to be able to upgrade to Full plan anytime during their subscription and only pay the difference ($10 regardless when they upgrade, not pro-rated).

Such feature is not available; we've prorating if the plans are in a parent > child relationship, but aside from this there's no specific priced prorating.

I found this thread - www.joomlapolis.com/forum/88-usage/12033...pgrade-plan-not-show and structure the plans as follows:

Plan 1 - Associate - $45/year, exclusive, no upgrade, no prorate
[Child] Plan 2 - Upgrade to Full - $10/year, non exclusive, upgrade, no prorate
Plan 3 - Full - $55/year, exclusive, upgrade, no prorate

This is your absolute best bet for providing $10 upgrade assuming Plan 2 is a copy of Plan 3 so they offer the same protection. I recommend setting Plan 1 and 3 to non-upgrade to prevent users from upgrading from Plan 2 to Plan 3.

Following the plan structure means member who sign up for Plan 1 and then later Plan 2 needs to renew both plans each year instead of being assigned Plan 3. This is not practical and won't make sense from member's point of view.

That would be correct, they would need to maintain both subscriptions. We've had an internal discussion to address such issues and are reviewing ways to resolve this with future releases so parent > child plans for instance could maintain same renewal rate.

Is there any other way to configure the plans?

Unfortunately not that I am aware of; the above would be the best approach given you'd like $10 upgrading fee.