If you use a fixed capacity but sell different types of tickets (for example child and adult tickets), it is recommended that these tickets are taken from the same maximum capacity.
Go to the desired event.
Go to Products.
Click Create new product or select an existing product from which nothing has been sold yet.
In the pool settings, choose the option Share a pool with an existing product.
Then select, in the drop-down menu, one of the other existing products with which the capacity should be shared.
Finally, click the pink button Create product or Save changes.
Need extra help creating a new product? Then also read this article.
Note: it is not possible to modify a pool after tickets have been sold.