Order of author names in a textbook that is to be published I am currently working on a book with several fellow researchers, and there seems to be a disagreement of how the author names should be listed. The book will be published by a major university press and will be listed on its website as well, so the order of names of the authors has become a touchy subject and disagreements ensued. I will describe everything in third-person to objectively portray the situation.

Z is the lead researcher of the project. Z has done more than 90% of the work and everyone seems to see this. Z is a professor.

A and B are staff researchers and their jobs were mostly editing and proofreading. A and B are professors as well.

U, V, W are graduate student researchers and have done the remaining 9% of the work, which were mostly grunt work that do not have particular intellectual value.

Now here is where the situation becomes sticky. The book made its way to a major press and A and B suddenly want a piece of the action. The problem is, Z's last name is the last in alphabetical order and making A and B authors will push Z's name to the back of the author list. While Z is considering adding A and B as the authors, U, V, W feel that A and B did not add much value to the book and therefore strongly believe that Z's name should appear in the front. Some even think that they themselves did more work than A or B, and A's name and B's name should not be listed as the author just like them.

Is there are way to resolve such issue? Is there a way to distinguish between the lead author and supporting authors, possibly by forcing the lead author's name to appear in the front? Or is there a way to make everyone authors of the book but make only the lead author's name appear in the book cover rendering the other two merely authors in name?
First of all, I agree with @tonysdg that A and B don't sound like they deserve any form of authorship. The same may be true about U, V and W, but I feel less strongly about that. So Z can simply argue his/her case forcefully, and if necessary appeal to the department chair or other outside objective parties. The facts are on Z's side, so I expect he/she will win the argument, though possibly at the risk of alienating his/her colleagues. 

Second of all, with regards to your comment that "The problem is, Z's last name is the last in alphabetical order and making A and B authors will push Z's name to the back of the author list", I don't see this as a problem at all. There is no rule that the list of author names on a book has to be in alphabetical order. So, it is perfectly acceptable and legitimate to list Z's name first, and indeed sounds like a very good idea (regardless of which other names end up being on the author list) considering that the project is overwhelmingly Z's intellectual offspring.

Third of all, one idea for an author byline that allows including minor authors but would still make clear the large disparity in contributions from the different authors is to use the "with contributions from" pattern, as in:


  The Great Book of Science
  
  By Z
  With contributions from U, V, W, [optionally:] A and B


See here for a real-life example.