The delegation method is performed the reference fields automatically set up on the parent model:
For example you can take idea from below code-

class Child0(models.Model):
    _name = 'delegation.child0'

    field_0 = fields.Integer()

class Child1(models.Model):
    _name = 'delegation.child1'

    field_1 = fields.Integer()

class Delegating(models.Model):
    _name = 'delegation.parent'

    _inherits = {
        'delegation.child0': 'child0_id',
        'delegation.child1': 'child1_id',
    }

    child0_id = fields.Many2one('delegation.child0', required=True, ondelete='cascade')
    child1_id = fields.Many2one('delegation.child1', required=True, ondelete='cascade')
        record = env['delegation.parent'].create({
            'child0_id': env['delegation.child0'].create({'field_0': 0}).id,
            'child1_id': env['delegation.child1'].create({'field_1': 1}).id,
        })
        record.field_0
        record.field_1