adding book multi format and metadata

[Khan-Dam]

Hello,

I want to add a big batch of ebook ( same as 2 or 3 Format for same book ) and add some informations placed in separate file

I Understand meta-data was read from file name or in each ebook file but :

what append if each book have not the same information in file name or as meta-data, example

booka.epub contain author = a
bookb.mobi contain author = b
bookc.opf have author c

so can someone explain clearly what the process of importing meta-data specialy what are used and what is the priority of data

2nd thing about opf dile does it readed always time when adding book ?
or just when book don't have meta-date inside ?

if yes can contain custom metadata ?

the idea is to produce for each book ( not each format ) a opf file that readed when adding book who contain information

or used in batch with ebook-meta

what the minimum in term of info for each custom metadata doeas i produce ( eg name and value or must have more info )

i'm a developer but not with python so i can make the necessary to produce the opf file.

sorry for my english ans asking to explain clearly but that is not my language

Regards

Cheers