Saving Associated Data

Need Help
1

Struggling a bit here with converting a CakePHP2 relationship to CakePHP4.

I have a member table, and each member can have one or more “Contacts” - these are parents / guardians or “next of kin” of a member.

In CakePHP we had a member_relationships table that held the parent_id and member_id

	public $belongsTo = [
		'ParentMember' => [
			'className' => 'Member',
			'foreignKey' => 'parent_id'
		],
		'ChildMember' => [
			'className' => 'Member',
			'foreignKey' => 'member_id'
		],

and in the member table

		'ParentRelationship' => [
			'className' => 'MemberRelationship',
			'dependent' => true
		],
		'ChildRelationship' => [
			'className' => 'MemberRelationship',
			'foreignKey' => 'parent_id',
			'dependent' => true
		],

All works fine.
In CakePHP4 I have

        $this->belongsTo('ParentMembers', [
            'className' => 'Members',
            'foreignKey' => 'parent_id',
        ]);

        $this->belongsTo('ChildMembers', [
            'className' => 'Members',
            'foreignKey' => 'member_id',
        ]);

and

        $this->hasMany('ParentRelationships', [
            'className' => 'MemberRelationships',
            'foreignKey' => 'member_id',
            'dependent' => true
        ]);
        $this->hasMany('ChildRelationships', [
            'className' => 'MemberRelationships',
            'foreignKey' => 'parent_id',
            'dependent' => true
        ]);

All is going fine except where I am trying to add a new relationship where a “Contact” (eg a parent) doesn’t exit- what I’m find is the id of the new Parent isn’t being saved in the parent_id field

        $memberRelationship = $this->MemberRelationships->newEmptyEntity();

        if ($this->request->is('post')) {
            $memberRelationship = $this->MemberRelationships->patchEntity($memberRelationship, $this->request->getData(), [
                'associated' => [
                    'ParentMembers'
                ]]);

I’m thinking the MemberRelationship record is being saved before the new “ParentMember” and so the parent_id is empty. Use to use “SaveAssociated” in CakePHP2