Syntax of have - already - yet

Solution 1:

In "you may have already arranged yet" it is not a question of tautology. "Yet" doesn't fit here at all in context with all else that has been written. You can say:

Thus, to avoid any clashes I would be very grateful if you could inform me about any dates you may have already arranged.

The word "yet" in this context pertains to the future, and if you were concerned about future dates you would use it like this:

Thus, to avoid any clashes I would be very grateful if you could inform me about any dates you may yet arrange.

In some cases, a final "yet" is used in a question to help ask if something expected has already been arranged.

Have you arranged any dates yet?