Missing entries in Dungeon guide - able to get added after dungeon completed?

I didn't realise that you could get an additional dungeon book even if you hadn't turned in an old one. I can remember at one point you could get missing entries added to the Hero Books (if you had done the quests without having the book in your bags). I have re done alot of the dungeons more than once (i tended to complete them Solo then go back in with guildies with a better knowledge of what we faced)

Guild wiki says on the subject

Completing dungeons without the Guide in your inventory will not add them to the Guide, but for 100gp per dungeon, the NPCs that give you the Guide can add the dungeons later on.

http://gw.gamewikis.org/wiki/Master_Dungeon_Guide

But i can't seem to get this done?

I have completed and turned in one dungeon book already and have started refilling another, but don't really want to have to repeat any i don't have to and get the credit in my book.

Help greatfully recieved!

AFAIK, you can't fill in two dungeon guides at the same time (except perhaps, 1 NM and 1 HM). You could try putting the partially filled one into storage (so it's not on you) and then go see if the NPC will add the pages to another one.

Any time you complete a dungeon or primary quest with a book in your inventory, it will be added to your book. If you do it with multiple books in your inventory, it will be added to the first book. This is true even for filled books, so if you had your full MDG in your inventory when you redid the dungeons, you can't add them - the game has already registered them as being "added". In other words, the option to pay to fill in pages you already completed works if and only if you had no books of that kind at all in your inventory when you finished the quest/dungeon.
Sorry, that's the way ANet set it up. =/