When you want to add more Devs and/or Cybers to an existing Cyber, you can click on the “update” button at the bottom left side of a Cyber on the Cybers page. The system to update Cybers is very similar to Creating Cybers.
You will have to pay the equivalent of the Mining Sessions needed (0.5 USD per Dev) for the remaining Mining Sessions of that Cyber, and also for the training fee (0.5 USD for each added Dev/Server). There are no discounts for Mining Sessions for 14 or 28 days when updating a Cyber. Remember that a Cyber can have maximum 10 Servers and that you need to add enough Servers to have sufficient capacity for the Devs you plan to add.
Here's an example: If you have a Cyber with 5 remaining Mining Sessions, and you add a new Dev, then you will need to pay 0.5 USD (training fee) + 3.75 USD (for 5 Mining Sessions) in $CRYPTO to add that Dev to your Cyber.
Another example: If you have a Cyber with 6 Mining Sessions remaining, and you add two new Devs and one Server, then you will need to pay 1.5 USD (0.5 USD x 3 training fee, because you are adding 2 Devs and 1 Server) + 9 USD (for 6 Mining Sessions x 2 Devs) in $CRYPTO to add those two Devs and one Server to your Cyber.