Replacing flow

Yes you can do this.  You’ll first want to add the new condition directly before the existing choice
 

Then add additional branches to that condition until you have the number of paths + 1 (temporary to hold the old multi choice) and an else branch
 

Then one by one you can drag the first node in the path down to merge them onto the condition.  Once the paths are merged you can right-click on the number inside the circle on the connector coming from the multi-choice and select ‘delete’.  You need to click on the text in the circle and not the circle itself for this to show up.
 

This will unhook your path from the old multi-choice node and only attached as a branch from the condition. repeat this step for the remaining paths.
 

Then you can delete the original multi-choice question, then delete the 1-st (now unoccupied) branch from the condition.