I currently have a live environment of 1 primary, 1 secondary and an arbiter. I need to do some protracted maintenance so I'm planning on adding another (temporary) secondary, synching up and then removing an original node to do the maintenance. When complete, the temporary box will be removed.
My question is about elections: when I add the temporary replica there should be an election, but at that moment I'll be transitioning from an odd to an even number of voters which should mean no primary is elected and my production database will be locked for writes. Is there a recommended process for adding and removing replicas to avoid election issues ?