merging two relation BelongsToMany and hasMany and returning relation

[galexpert]

hi, it is possible to support merging two relation BelongsToMany and hasMany and returning relation laravel.
I need to merge two relationships (take and merge records from one table using different relationships...) and return the relationship in order to be able to perform actions with them... and then the method ->paginate($perPage, ['*'], 'page', $pageCurrent);

For example
There are item and seller models
seller.php

public function items()
   {
       return $this->belongsToMany(Item::class, 'item_seller', 'seller_id', 'item_id')->withPivot('id', 'enabled');
   }

public function myItems()
   {
       return $this->hasMany(Item::class, 'seller_id');
   }

I need to combine these two relations and return something similar

public function ALL_items_merged()
    {
        return $this->myItems() + $this-> items()
    }

$seller->ALL_items_merged()

for further work with this relationship
Thanks for any tips or solutions