If writing in a Descriptive Book simply links to an age, then how does editing that book change the linked age?

In both the books and games of the Myst series, it is established that Descriptive Books do not create worlds, but simply link to already created worlds.

If this is true, then wouldn't editing a Descriptive Book change the link to a different world, not alter the preexisting age? If it is indeed linking to a different age, then how can that be reconciled with a Descriptive Book being altered while main characters are in the age and meeting up with them later with them having visually watched the changes happen? If one changes a descriptive book and then goes into the age, their linking book is still in the last place they hid it as well.

Example: In Myst: The Book of Atrus...

Gehn believes that they create worlds, yet Atrus (who we are to believe is smarter and more logical) thinks the worlds already exist and that they are simply linking to them. This fact is repeated throughout the games and books without Atrus ever being convinced that Gehn may have been right. However, the only way I can seem to make the editing of a descriptive book work is to follow Gehn's theory.

Using Atrus' theory: If writing in a Descriptive Book simply links to an age, then how does editing that book change the linked age?