@Colleen253
Yes, you need to do it two steps.
This my view on this:
Changing the listing will actually mean a new booking, it is not just an update on the current booking.
After the new booking is settled, the next change can update options related to this listing.
It works the other way round, as the "old" listing allows decrease of amount of guests.
But increase only works if the max. setting is read form the new listing, which is not performed at the moment of entering the change of listing.