upgrade asset store price

I want to upgrade one of my asset, sell the upgrade at the same
price, and make it free for anyone that have already buy the last

What must i write in the create Paid package upgrade price ?
The same amount of money ? Or is it cumulative ? Package price +
upgrade price so i have to write 0 ?

Also is it possible to enter an infinite grace day ? Maybe with -1 ?

Thanks for any answers !)

i was wrong… To update an asset and keeping the same price,
we must not use the upgrade tab of the asset store publisher.
But create a new draft of the package. Upload the new asset
in this package, change eventually metadata and key image.
Then resubmit the asset. The asset will be upgraded after an
approval !