Item count multiply extras

Hi, We purchased the developper version but we have a problem with the item count. In the demo, Adults and Children are in extras , so we kept it that way , but if someone book an activity for 2adults and 2 children, it updates the calendar – 1 item available , even if there are 4 persons booked. And when we put 4 items , and we choose 2 adults and 2 children , it updates the calendar – 4 but multiply the price as if we bought 4 items, each with 2 adults and 2 children.

Is there a way to make the calendar update available seats without having the price multiplied by the number of extras ?

thank you

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