Ok.
Let’s ask again.
Is 128 patterns enough space for you to write album/live set/late night space funk rituals?
If yes, where is the problem? Simply organise your patterns on both machines accordingly.
If no. Why?
These are both rhetorical questions. Have a think. Sleep on it maybe. The solution is very simple.
I start to be short of explanations about my issue.
The problem is not to organize or to lack of patterns. As i told you i just need like 12 patterns.
I also have a clear idea of my organization. I want A09 on the DN when I switch to BANK 9 on the OT.
Is this possible or not?
No.
12 patterns needed.
Just use bank A on both machines.
Solved.
Thanks for the clear answer 
Well, i guess i can always try to make 12 songs with only 4 parts…
Indeed.
The DN can change its pattern in response to a MIDI Program Change (PC) message. If you want it to change to pattern A09, then it needs to receive a PC message with value 8 a short time before the new pattern should start. (The DN does not respond to Bank Select messages, so it is pointless trying to send values of BANK or SBNK from the OT to the DN.)
The OT can send PC messages in two ways:
The first way will do what you want: the pattern change will happen on time (except for some exceptional circumstances involving settings on the DN).
The second way will not work for you because the PC message is sent too late for the DN to queue the next pattern. (This way is more appropriate for changing patches on a synth.)
That’s why we have been recommending to you that you use the first method, align the patterns on both instruments, and ignore trying to map across banks. If you only need a handful of patterns at a time, then you should easily be able to fit them into the 128 patterns (and 32 Parts on the OT) available in banks A to H on both instruments.
Here again you are confused by the terminology. If you use the first method described above, then switching to pattern A09 or pattern I09 on the OT will cause pattern A09 on the DN to launch.
Thank you very much for the detailed answer.
Already i did not know that.
If i’m correct that is what i’d call the auto-synchronization, A01 > B01 switches automatically the same way on the DN. Same dor A09 to B06 for instance.
The problem occurs when i want to use the 8 last banks on the OT (no more pattern available on the DN).
That’s why i was trying to use « mapping », the second way you’re speaking about:
When i use this way for a synth, it doesn’t wait and changes automatically on a synth. That’s why i could not understand it is not the same for a pattern.
As I said above, i still need 12 different parts so the organization 1 song = 1 bank cannot work.
I think the only workaround is to think 1 part = 1 song so i can fit for instance 4 songs within a Bank and keep the patterns aligned with the DN.
Thanks to both of you for taking the time of explaining, i really appreciate.
But on the OT there are 4 Parts for each bank of 16 patterns. And since the OT and DN have 8 banks (A to H) in common, you can use 32 different Parts on the OT, with all the associated patterns (A01 to H16) aligned on both machines, and no need to worry about banks I to P on the OT.
Just a shame i have to use a workaround instead of what seemed to be a natural behaviour.
I’d’need to rework all my set according song=part and not song=bank and copy loads of stuff.