Q308: I need to keep track of the number of persons (or adults and children separately)

The first thing to consider is what is your resource type. If your resource is of the "shared" type (as set in your resource settings), meaning per-person units (tickets/seats/course places etc.), then you don't need to configure anything -- iBookfishing will automatically replace the words such as "quantity" with "number of persons" on the reservation form and will automatically keep track of the number of places left for given time unit.

If your resource is not of the shared type, meaning a single reservation for an entire group of people, for example a cottage/vacation home for rent, and you need to keep track of all the persons arriving (to properly set the pricing or to register the personal details), you will need to configure the number of persons as a custom resource property (see also Q154) AND as reservation form item(s) (see also Q142) as follows:

Custom resource property
You need to add a custom resource property of type number of persons (here). This will be the max capacity of your resource which you will be able to use for example in a search form or in filtered resource listings. This way a customer will only see the resources that can accommodate for the group size. If in your custom resource property's search condition you enter >=, then the search form will return resources with the searched or greater capacity (e.g. a 3-bed room when searching for 2 persons).

Reservation form items
Defining a custom resource property is not enough if you need to register the number of persons for a reservation, or if you need to register personal details of each person. In order to get this data, you'll need to add a reservation form field (here) of type number of persons OR multiple fields of type number of adults and number of children -- note that you can ask separately for different age groups this way.

If you need to register personal details, the best way is to add an item of type section for each participant. Inside this new section you can define any number of fields, e.g. participant name, age, sex etc. If you only need the names, instead of this section you can simply add a single item of type participant names. In both cases, the number of fields displayed will depend on the dropdowns number of persons or number of adults/children so that details of each participant can be registered.

Note that when the customer starts the process by using the search function with the number of persons dropdown, iBookfishing will automatically prefill the number of persons field with the value chosen in the search form. Also, if your pricing depends on the number of persons in the group, the search results will apply these pricing rules to the price displayed in search results.

Pricing
See Q276 in the FAQ for detailed instructions for configuring pricing based on the persons present in the group (including separate pricing for adults and children). Note that iBookfishing understands the meaning of all personal fields (of type number of persons / adults / children) and so the rules and prices entered in Pricing Manager can use criteria such as per person even if you only have fields for the number of adults/children.