Overriding classes with class_alias - php

Question

I know this is a really bad idea, but I ran out of ideas, so I'd like to hear some opinions about it.
I'm working on a PHP project which allows the development of addons so that other developers can add their own functions, not so different from thousands of other open-source projects:
root
└── addons
└── addon-a
└── addon-b
└── addon-c
I have to implement some changes to an already made addon (let's say Addon A) without changing the original files or using Composer PSR-4. Unfortunately, the original author did not follow good practices that would help to accomplish this task. Here's how the Addon A is:
Structure
addon-a
└── main.php
└── classes
└── Foo.php
└── Bar.php
addon-a/main.php
include_once __DIR__ . '/classes/Foo.php';
function run() {
echo AddonA\Classes\Foo::returnTwo();
}
addon-a/classes/Foo.php
namespace AddonA\Classes
use AddonA\OtherFolder\FooBar
abstract class Foo {
public static function returnTwo() {
return 2;
}
public static function returnFooBar() {
return new FooBar();
}
}
I need to override the returnTwo function and return another value. Without changing other files, the only way I was able to do it was through the class_alias method, copying the whole Foo class:
First, I created another addon and made it ran before the Addon A "run" function:
Structure
new-addon-a
└── main.php
└── classes
└── Foo.php
new-addon-a/main.php
function init() {
include_once __DIR__ . '/classes/Foo.php';
class_alias( 'NewAddonA\Classes\Foo', 'AddonA\Classes\Foo', true );
}
init();
new-addon-a/classes/Foo.php
namespace NewAddonA\Classes
use AddonA\OtherFolder\FooBar // No changes to the previous "uses."
abstract class Foo {
public static function returnTwo() {
return 3;
}
public static function returnBar() {
return new AddonA\Classes\Bar(); // Here I had to change because the namespace has changed
}
}
Now, when Addon A executes the function run, the AddonA\Classes\Foo::returnTwo will be my own class.
Well, as I said before, this is pretty ugly, and I would lose any update to the Foo code since I'm overriding the entire class. However, this was the only way I thought. Do you think it would be possible to use another method?
Thanks!