I need to retrieve the UID

How can I select the specific bullet object (with bullet behavior) that my enemy object spawns?

SYSTEM: Pick by comparison: Pick Bullet object where Bullet.UID = what?

Just store the UID when you spawn it. Use an instance variable on the Enemy, if that makes sense. This is only if there is one bullet at a time. Otherwise, you'll have to provide more details on what you are trying to do.

Enemy.StoredBulletUID = Bullet.UID

wait, I store the UID of the bullet to the enemy's instance variable? Did I get that correctly?

Well, there are many instances of the same gunman object enemy at the same time, so that's why I need to know the specific bullet shot by each enemy. Is what you said correct for my situation?

In that case, you need the opposite. If you want to know who shot which bullet, you store the Enemies UID on the bullet.