Hacking [Question] How to transfer retail save to digital on unlinked system?

[Brewzip]

I have some retail games that i want to play as CIA and I want to transfer their saves across the two version.
Most important is retail to digital, but I would like to do even the opposite.
Some saves are 128KB card1 (eg. Super Mario 3D Land), someone started below, and someone after updating to 6.x firmware.
I have also card2 saves (Pokemon XYORAS) that uses 6.x encryption.

I've tryed some stuff to import the saves to CIA, but none of them works.
SaveDataFiler works only in Gateway Mode, but it cannot recognize my retail card.
In Classic/rxMode it's the opposite, the card is found, but SDF CIA is unsigned and can't run.
I've tryed to extract the save with the Gateway Tool for card1 saves, fill them with an hex editor to match 512KB, rename the save correctly, select the dump on Rom Selector and then run SaveDataFiler.
I cannot use the save plugin of any CFWs, because I have an Old 3DS with unlinked sysNAND 9.x.

Later I'll try to temporary update to 9.6 and download the official savedata transfer tool from the eShop.
However this method (if it works) will allow me to only transfer retait to digital. Since I want to keep my retail save, that would work only for card1 saves, because I can reinsert it with Gateway Tool.

Has someone solved this problem? Thank you guys!

 

[tipsytoto]

Below is based on my understanding of what is available and I have no idea if it will work.

So, use the latest emunandtool to backup your current emunand.
Then save contents of current SD card.
Use gateway menu to format emunand(aka create a new linked emunand)
use bigbluemenu.3ds/cia + savedatafiler.cia in the newly created emunand to get the save data.
Backup said save data and then just use emunandtool to inject your original unlinked emunand back into the SD card and restore your original SD card contents.
Then in gateway mode use savedatafiler to import the saves?

 

[Brewzip]

use bigbluemenu.3ds/cia + savedatafiler.cia in the newly created emunand to get the save data.

It won't work, because Gateway Mode don't find the retail card and Classic Mode don't allow to use SaveDataFiler.

 

[Brewzip]

The savedata transfer tool from the eShop worked, but my problem is still not solved, because I cannot reinject the save in the retail card.