Ah ok, thanks for clarifying.
With the new calendar-based vessel scheduling (which replaced the old way of picking two vessels), you can schedule as many vessels as you need (you could do 100 if you really wanted).
You can just keep “drawing lines” on the calendar to add another vessel. The guide at How to plan which vessels will be used on a beer batch should hopefully explain this in more detail (I’ve just updated it to make this clearer).
If you still need a hand with this, please let me know 