Instead of using the ChapterNum tag and AppendixNum tag ,just use the normal format as <n+> and a \t like you do narmally making sur when you put in that you do like H:<n+> and when you create one for volumes or any other you use some building blocks starting with a different alphabet like B:<n+><\t><\t>.
Its just an example ,you can use you own and then apply it .
Thanks Harpreet. I did try the method you described and the chapter numbers where being incremented after each part file. Do you know what are the <$volnum> building blocks used for? What about the Volume tab in the Numbering menu. I used all of these and still can't get the part numbers to increment on their own and chapter numbers continuous. The part tag is in it's own file and it's just a part para tag on an empty page, similar to having a partion in a multi volume book.