Subscription price change and preserving existing subscriptions

I have the following scenario:

  1. I had a subscription price of $10.
  2. I increased the price to $20 for new subscriptions, while preserving existing subscriptions price ($10).

Now, I want to decrease the price to $15:

I understand that existing $20 subscriptions will automatically renew their subscription for the reduced price ($15).

BUT, what will happen to the existing $10 subscriptions? I get no option to preserve or increase their price when trying to change the price to $15.

Subscription price change and preserving existing subscriptions
 
 
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