update api register

app/Models/CustomerUserLink.php

@@ -0,0 +1,30 @@
+<?php
+
+namespace App\Models;
+
+use Illuminate\Database\Eloquent\Model;
+
+class CustomerUserLink extends Model
+{
+    protected $guarded = ['id'];
+
+    protected function casts(): array
+    {
+        return ['is_primary' => 'boolean'];
+    }
+
+    public function customer()
+    {
+        return $this->belongsTo(Customer::class);
+    }
+
+    public function user()
+    {
+        return $this->belongsTo(User::class);
+    }
+
+    public function tenant()
+    {
+        return $this->belongsTo(Tenant::class);
+    }
+}