Prorata rate for Product Add on

Hi,
In my system, I am using the product add on as an annual recurrence maintenance for specific product.

Situation :
Product A (price A)=> product A add on (price PA)
Product B (price B) => product B add on(price PB)

Upgrade before it reach 1 year or before the product addon due :
Product : Price B - Price A = new price (which is correct / no prorata)
Product add on : price PB - prorata price PA = new price (which is my issue)

My issue

Upgrade Product A to B, the product add on price was not calculated based on Prorata rate.
Is there any solution to make it calculate the prorata rate between those 2 product addon?

I know we have the prorata option for the products and configurable options, but in this case, I want to use the add on.

Is there any possible solution other than buying an addon for this?