Is extending a model to multiple classes possible?

To use Mongodb my model needs to have:

...
use Jenssegers\Mongodb\Eloquent\Model as Eloquent;

class User extends Eloquent
...

my User Model looks like this:

<?php

namespace App;

use Illuminate\Notifications\Notifiable;
use Illuminate\Foundation\Auth\User as Authenticatable;
use Laravel\Passport\HasApiTokens;
use Jenssegers\Mongodb\Eloquent\Model as Eloquent;

class User extends Authenticatable
{
    use Notifiable, HasApiTokens;

    /**
     * The attributes that are mass assignable.
     *
     * @var array
     */
    protected $fillable = [
        'name', 'email', 'password',
    ];

    /**
     * The attributes that should be hidden for arrays.
     *
     * @var array
     */
    protected $hidden = [
        'password', 'remember_token',
    ];

    public function property() {

        return $this->hasMany('App\Property', 'userid');

    }
}

when I change Authenticatable to Eloquent I get this error:

Argument 1 passed to Illuminate\Auth\EloquentUserProvider::validateCredentials() must be an instance of Illuminate\Contracts\Auth\Authenticatable, instance of App\User given, called in /home/ubuntu/xxx/vendor/laravel/framework/src/Illuminate/Auth/SessionGuard.php on line 377

when I leave it as Authenticatable, I get this error:

"Call to a member function prepare() on null"

which is normally what happens when I don't include it..

Any ideas how I can make this work?