If an offer for this product already exists, it is updated.

OfferAmount is the maximum cumulative number of orders that a supplier can receive for this product. Currently approved cumulative offer amount is located in the nested meta object together with the amount of shipped and reserved items.

Example:

A new offer is created with offerAmount = 10
5 items are sold, 3 of which are shipped and 2 are reserved. It means the offerAmount value cannot go below 5 anymore.
To increase the offerAmount by 5, you take the old offerAmount (10) and add the increase value (5) = 15.
The increase should first go through the approval process.
No approval needed for decrease, but it should not be lower than shipped + reserved