Ofc, you just need a text editor to use DDF.
The difficulty depend of the OS.
There is 2 folders to put DDF
All DDF provided directly with deCONZ typically reside in
/usr/share/deCONZ/devices/on a Linux system and are loaded first. However, files residing in the home directory of the user running deCONZ (e.g./home/<DECONZUSER>/.local/share/dresden-elektronik/deCONZ/devices) will override the pre-packaged files to allow users to amend and keep their own files if desired.
On HA it’s harder because the first folder is not persistent and the second folder is hidden How to add/edit a DDF on Home assistant using text editor?
So for you no choice, you need to install DDF on the folder in “data” to overwrite the official deconz one.
After depend of your issue.
If you just miss the Fyrtur, install this DDF DDF for Ikea Fyrtur roller blind by SwoopX · Pull Request #6110 · dresden-elektronik/deconz-rest-plugin · GitHub
If you miss both, you need too edit the existing “kadrilj_blind.json” and change the status from “Bronze” to “Gold” (Or remake one with the good status if you have HA).
After that just restart deconz, and re-nclude the device.
If you have the GUI can take the “Hot Reload” on the editor menu.