Merging private subkeys into other key

[Viktor Dick]

Hi,
there has already been a discussion on this two years ago, see
https://lists.gnupg.org/pipermail/gnupg-users/2013-September/047567.html

I have been following the intstructions on
https://wiki.debian.org/Subkeys for some time now, with my master key
only residing on my backup disk and several machines having only the
subkeys. But now I somehow have the problem that only an older version
of the master key is still there, so I have one keyring with the master
secret key but without the most recent subkeys and another with the most
recent subkeys but without the master key. Does anyone have an idea how
to merge them? Using --import results in
###
gpg: Total number processed: 2
gpg:              unchanged: 1
gpg:       secret keys read: 2
###
I also tried
###
$ gpg --homedir /mnt/backup/.gnupg --expert --edit-key <keyid>
gpg> addkey
Please select what kind of key you want:
....
  (13) Existing key
Your selection? 13
Enter the keygrip: <output from gpg --with-keygrip -K>
No key with this keygrip
###

I am not sure what the keygrip is, but I guess it is only valid within
the same keyring or something?

Any help is greatly appreciated. In a month or so I need to create new
subkeys and I would rather not lose my current subkeys.

Regards,
Viktor



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