Vine Clarification

Hello,
Ok so i have been looking into Vine and there is a whole host of information online but both amazons instructions and online all say the same quote.

“We will charge a 140 GBP enrolment fee for each enrolled parent ASIN starting October 12, 2021 and display the enrolment fee at the time of enrolment. The fee will be charged once per parent ASIN, seven days after the publication date of the first Vine review for that product.”

It would be nice to have some clarification on this as the word Parent throws me off…

I have around 25 Parent Asins on my FBA Account linked to around 140 Child asins, Surely this does not mean that i could link a Parent Asin which then enrols my child asins?

I Understand that Vine does not guarantee a review but let’s say an item gets 10 reviews, I am right in saying that this means that after the first review I am charged 140gbp and every review thereafter is free of charge up to 30 reviews ( therefore in my example equating to an average of 14gbp per review)

Thank you