Create new certs for old stack

Hello All,

I have a scenario where I created a stack with following this link

Here are the answers I am looking for,

  1. How to create new certs for the entire stack and migrated all the indices? Please note I dont have old ca.key. The website above wont mention anything about it.
  2. How to add new nodes to the stack?

Please help me on this at your earliest.