User optimisation and code cleanup

app/Models/Rtm.php

@@ -4,6 +4,7 @@ namespace App\Models;
 
 use Illuminate\Database\Eloquent\Factories\HasFactory;
 use Illuminate\Database\Eloquent\Model;
+use Illuminate\Support\Collection;
 
 class Rtm extends Model
 {
@@ -23,4 +24,20 @@ class Rtm extends Model
 	{
 		return $this->hasMany(self::class,'parent_id');
 	}
+
+	/**
+	 * Return all the children RTM records that this record is parent of
+	 *
+	 * @return Collection
+	 */
+	public function children_all(): Collection
+	{
+		$result = collect();
+		$result->push($this->withoutRelations());
+
+		foreach ($this->children as $o)
+			$result = $result->merge($o->children_all());
+
+		return $result;
+	}
 }