At the beginning you have to setup your cold wallets (securely).
Don't create them on an online machine and move them to a cold storage afterwards.
Do create them directly on your (always) offline machine.
Then, to create a transaction from your offline PC without the synced blockchain you can follow this small guide by dexX7:
https://bitcointalk.org/index.php?topic=651344.msg7306076#msg7306076.
He has explained it pretty detailed.
Feel free to ask for further questions.
Essentially I want to move from one cold wallet to many cold wallets for increased security and usability.
You don't necessarily increase the security by setting up multiple cold wallets.
Additionally the usability decreases (in my opinion).
You might try out this setup:
- 1 offline PC with several electrum[1]-wallets
- 1 online PC with a watch-only wallet containing all the xpub keys of your cold storage wallets.
This way you will be able to easily spend from your cold storage (create TX from your (onine) watch-only wallet), then move the TX to your cold storage (either by QR+webcam or USB), then sign the transaction on your offline PC, move it to your online PC, broadcast it.
And you will still be able to manage your several cold wallets seperately.
I think it is more user friendly to use an offline setup like this with electrum [1] than using core.
[1]
https://electrum.org/#home