How to add another disk to existed root luks with btrfs?

Hello everyone!

I am trying to add another disc to the root partition. Root was encrypted during installation. And after reboot I get error:

Slot 0 opened
Error: no signature.
Going into rescue mode...

Notebook with dual SSD

What I did before:

  1. Install Manjaro and select “Wipe all disks” option, select btrfs and set password for encryption.

  2. After booting to system, create a LUKS partition on another SSD with the key generated during the installation step.
    cryptsetup -v -c aes-xts-plain64 -h sha512 -s 512 luksFormat /dev/nvme1n1p1 /crypt_key.bin.

  3. Next step is to add this to /etc/cryptab. On the new line, write the same data as for root, except UUID and name. Get the UUID from the command. Then reboot (I know this is not nessesary, but just to make sure it unlocks correctly after boot)
    blkid /dev/nvme1n1p1.

  4. After adding the btrfs partition to root
    btrfs device add -f /dev/mapper/ssd2 /

  5. Next step, run balance
    btrfs filesystem balance /

  6. Last step, update grub. Easy way to add new disc to grub script (seems to me)

Maybe I am doing something wrong or missing an important step. I don’t know.

Anyone could help me pls understand what I am doing wrong?