How-to merge local pools into one BD XL ?

[Alexey Eromenko <al4321@gmail.com>]

Hello,

I want to make one big BD XL (100 GB) image of Debian.
I have downloaded 3 Blue-Rays of Debian 8 (amd64).

Before (re-) mastering my BD XL image I need to create one big repository.
How do I merge those into one repo / pool ?

Thanks in advance,
-- 
-Alexey Eromenko "Technologov"