Hi - you can change triggers at any time, and Marketo will just pick up the changes. If you do want it to stop triggering while you work out changes, the only way to do this is to deactivate the trigger in the schedule tab, make the changes, then reactivating the trigger.
Thanks for the answer Veronica. I am new to Marketo as you can probably tell 🙂 I'm afraid I didn't explain the issue properly - I meant to ask about changing Flow stages during a campaign. This was done and the campaign was paused, I received the following notification:
Hi - was this a batch campaign that was halfway through running when you made this change? If so yes, the campaign will abort. You can schedule it to run again, but ensure that you have the campaign settings set to "leads can only flow through the flow once" so nobody gets the same smart campaign twice when you run it again.