After I've agreed to mail the books, but before I print of the wrapper,

Can the requestor cancel a book.

I ask as the requestor has requested a whole set of books, one of which is a book I have a duplicate (same ISBN etc) so I've only got one listed for now.

If he/she can cancel the book I'd send the duplicate as a freebie so that I can keep my place in FIFO for the other.

I'm not sure whether you want them to cancel or not to be able to cancel. I know that as soon as you've viewed the address (don't have to literally print it yet), the requestor can no longer cancel the request. You'd have to cancel it on your end, which I suppose would take your book out of the FIFO queue.

I haven't even looked at the address yet, I have simply said I can mail later (at the farthest date out), so that I could at least get the ability to PM the member.

If you have marked "yes, I can mail", but, have not yet clicked the link to display  the address - regardless of whether you actually printed it -  then the requestor can still cancel.

Also if you cancel then it'll roll the request for that book over to the next person who has it posted.  Better for the requestor to cancel on their end.

Thank you so much,

There was a time when I would have been able to answer that myself, but I've been away (on vacation hold) for so long I couldn't remember anymore.

I had someone order 4 books.  When I went to mail them I noticed one had minor water marks.  I asked the person to cancel that book only and I would send it along as a freebie. She cancelled; I sent the books.  Everyone was happy.

IIRC, until the sender prints/views the shipping label the requestor should have access to a 'cancel' button.