No matter what you do, entrenched engineers will make SURE they will be the only ones maintaining everything until their retirement, because they will make life impossible for everybody else until they leave.

Entrenched engineers don’t want to you to alleviate or god forbid share the pain. Pain is good for employment security. And if the ship goes down, they’ll make sure they’re the last one to get fired, because there’s nothing the entrenched engineer fears more than having to job hunt.