I just posted a WL book. It apparently skipped the first person and went to the next person in line. The book is the first in a series -- actually the first book in a series that's a spinoff of another series.

I am currently reading and about to finsih the second book, which is also a WL book. The requester happens to have Book 2 on her WL. Can I PM her and ask if she would like me to post that to her WL, or is that violating the whole WL and FIFO thing? I don't want to break the rules, or circumvent the system, but it would be nice to save some postage and in the meantime send this woman both books so she can read them back-to-back, if she wants.

I appreciate any input on this.

Thanks!

It's not any sort of violation of PBS rules.  You are free to post your books to anyone you like FIFO or through direct posting to someones WL.  If it were not OK, the wishlists wouldn't be viewable by others or have the POST THIS BOOK tab for each entry.  Some members make their WL private and unviewable and may miss out of offers like what you're doing.   It's your book to do with what you want.   I do it all the time when I get a request from my shelf or from the posts I make on the "Is this on your WL?" threads.   I'm trying to save postage and move some books.  I do always pm and ask before posting an unexpected book to anyone first. 

I had a box of books to send out to a member--did a deal for them--and looked through her wl and noticed that I had a book on her WL I could post to her.  I pm'd her first and she declined at the moment.  You just never know so it never hurts to take a minute to ask.

Yes, It's fine to offer a WL book to anyone you like.

In fact, I recently asked someone that had ordered a book from me. I noticed that I had something that was on her WL. My book wasn't the version she wanted (large print) but she appreciated the offer.

Technically you don't even have to PM, you could just post it right to them. I always PM though and like to be PM'd.  Some people carefully plan credits and not asking first cold mean them having to buy a credit, use the Not Now option or decliine another WL offer or something when they may have been far down the list on that 2nd book.

I always check requestors' WLs to see if I have other books that they want. If so, then I PM them offering to send them the additional book(s). As Mary said, you could just post directly to their WL but I think it's much more polite to give them the option in case they don't have the credits. But it's usually a win-win -- you save on postage and the requestor receives a WL book sooner than expected.

I too always check other members WL; it's even part of my profile and it saves postage $!

I do recommend PMing the person to make sure they have the credits or that they still want the book.  I'm sometimes surprised by books I've accidently left on my own WL.

Yes you can do this. It's always a good idea to PM the member first though, after they accept the first offer, because some may wait due to credit availability or even some have waited to find out if they liked first in series before ordering anymore. Though it's easier to get rid of WL books, they may want to wait for whatever reason.