When to apply it? If you don’t mind, please explain.
Hi, you might need that if you create two different objects and, for example, want them to do the same action together. For instance, if you create a random amount of an object and want to attach another object to each of the instances, you need to use the link-objects action.
There are more use cases and the documentation is explaining that:
http://wiki.compilgames.net/doku.php/gdevelop5/all-features/linked-objects