Patch different entities according to a selected option in a select tag in cakephp 4.4

I have two tables with a hasmany association (Events and Schedules, foreing key schedule_id in Events), also I have a hasmany association between Events and EventsUsers, and this last one has a hasmany association with Users and Pacients, I have 4 schedules, one is for Users and the other three are for Pacients, so when I select the schedule for Users I show a grid with the users and when I select the three schedules for pacients I show a select where I choose one pacient, I use jquery to show or hide the grid or the select, but when I submit the form for a pacient it sends all the users and I only want to send one user, how can I do that?
This is the code for add view:

 * @var \App\View\AppView $this
 * @var \App\Model\Entity\Event $event
 * @var \Cake\Collection\CollectionInterface|string[] $groups
 * @var \Cake\Collection\CollectionInterface|string[] $nets
 * @var \Cake\Collection\CollectionInterface|string[] $schedules
 * @var \Cake\Collection\CollectionInterface|string[] $users
<div class="row">
    <div class="column-responsive column-80">
        <div class="events form content">
            <?= $this->Form->create($event) ?>
                <legend><?= __('Agregar Evento') ?></legend>
					echo $this->Form->control('description',['label'=>'Descripción del evento']);
					echo $this->Form->control('schedule_id',['label'=>'Agenda','empty' => '-- Seleccionar agenda --']);
					echo '<div id="selectPacient" style="display:none;">';
					echo $this->Form->control('events_users.0.pacient_id',['label'=>'Paciente','options'=>$pacients,'empty' => '-- Seleccionar paciente --']);
					echo $this->Form->hidden('events_users.0.user_id', ['value' => $viewUser["id"]]);
					echo $this->Form->control('events_users.0.observation', ['label' => 'Observación']);
					echo '</div>';
				<div id="selectUser" style="display:none;">
					<div class="table-responsive">
								foreach ($users as $user):
								<td><?= $user->full_name ?></td>
								<td><?= $user->profile->name ?></td>
										foreach ($supplies as $supply):
											echo $supply->description;
											echo $this->Form->control('events_users.'.$i.'.quantity',['label' => false, 'placeholder'=>'Ingrese la cantidad']);
											echo $this->Form->date('events_users.'.$i.'.deliver_date', ['class' => 'form-date']);
											echo $this->Form->hidden('events_users.'.$i.'.user_id',['value'=>$user->id]);
											echo $this->Form->hidden('events_users.'.$i.'.supply_id',['value'=>$supply->id]);
							<?php endforeach; ?>
			<?= $this->Form->button(__('Guardar')) ?>
			<?= $this->Form->end() ?>
		var schedule_id = $(this).val();
			case '1': $('#selectPacient').hide();$('#selectUser').show();
			default: $('#selectPacient').show();$('#selectUser').hide();

And this is the code for add action:

    public function add()
        $event = $this->Events->newEmptyEntity();
		if ($this->request->is('post')) {
			$event = $this->Events->newEntity($this->request->getData(), ['associated' => ['EventsUsers']]);
			$event->group_id = $this->controllerUser['group_id'];
			$event->net_id = $this->controllerUser['net_id'];
			$event->main_gate = $this->controllerUser['main_gate'];
			if ($this->Events->save($event)) {
					if($event->schedule_id > 1){
						$user_id = $this->request->getData('events_users.0.user_id');
						$pacient_id = $this->request->getData('events_users.0.pacient_id');
						$observation = $this->request->getData('events_users.0.observation');
						$event->event_users->event_id = $event->id;
						$event->event_users->user_id = $user_id;
						$event->event_users->pacient_id = $pacient_id;
						$event->event_users->observation = $observation;
						foreach($event->events_users as $key => $user){
							if(!empty($this->request->getData('events_users.'.$key.'.quantity')) && 
								$user->event_id = $event->id;
				$this->Flash->success(__('El evento ha sido creado'));
				return $this->redirect(['action' => 'index']);
			$this->Flash->error(__('No se pudo crear el evento. Por favor, intente nuevamente'));
		$pacients = $this->Events->EventsUsers->Pacients->find('list')->where(['Pacients.group_id' => $this->controllerUser['group_id'], 
			'Pacients.net_id' => $this->controllerUser['net_id'], 'Pacients.main_gate' => $this->controllerUser['main_gate']]);
		$users = $this->Events->EventsUsers->Users->find('all')->contain('Profiles')->leftJoinWith('Groups')->where(['GroupsUsers.group_id' => $this->controllerUser['group_id'],
			'GroupsUsers.net_id' => $this->controllerUser['net_id'],'GroupsUsers.main_gate' => $this->controllerUser['main_gate']]);
		$supplies = $this->Events->EventsUsers->Supplies->find('all');
		$schedules = $this->Events->Schedules->find('list');
		$this->set(compact('event', 'pacients', 'users', 'supplies', 'schedules'));

So, you have a form with a bunch of fields in it, and when you submit that form it is sending you all those fields? That’s how forms work. If you want to block some fields from being sent you either needs multiple forms and submit only one, or use JS to disable the fields you don’t want to send. Alternately, you might include some extra fields somehow that would tell your controller what data it should use and what to ignore.

Thank you @Zuluru I could solve it with beforeMarshal in the Table class.