Validate rules and reactdatepicker configuration

Hi.

I’m having trouble customizing a donation form.
I need to add two fields to it.
One to register for a donor’s birthday.
And a second one to register the ID number of the donor.
Before proceeding with the donation, both fields have to be checked to verify that the donor is over 18. Some numbers in the ID value must match the month and year of the birthday value.

So far, I have created 2 custom fields : date and text :

add_action('givewp_donation_form_schema', static function (Give\Framework\FieldsAPI\DonationForm $form) {

// birthday
$field_date = Give\Framework\FieldsAPI\Date::make('birthday')
->showInReceipt()
->label('Birthday')
->placeholder('01/01/1970') // placeholder not working on date field by the way
->dateFormat('dd/mm/yyyy')
->required()
// ->rules()
->showInAdmin();

// id
$field_id_num = Give\Framework\FieldsAPI\Text::make('id_num')
->showInReceipt()
->label('ID Number')
->placeholder('95052125896')
->required()
->maxLength(11)
->minLength(11)
->showInAdmin();

$form->insertBefore('donationAmount', $field_date);
$form->insertAfter('birthday', $field_id_num);

});

I’m currently stuck to limit birthday selection to years overs 18 and to check the values.

reactdatepicker, used in the date field, is able to exclude date intervals:
https://reactdatepicker.com/#example-exclude-date-intervals
How could I “override” the default configuration to achieve this?

It seems that Give has tools to validate rules (->rules() / HasValidationRules), but I can’t find resources to make it work.
I also tried to load a custom javascript to the form to check values this way, but I only managed to load it on the confirmation step.
Could you, please, describe how to use the validation rules and/or to enqueue a custom script on the form?

Kind regards.
Gérôme

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