B2B Adjusting segments. Considered a new booking or not?

[Kenhel]

We are currently booked on B2B cruises in August and September 2024: a 14-day Rome to Barcelona and a 25-day Barcelona to Ft Lauderdale on Sun Princess (same cabin for both cruises).  We see on various booking sites that these cruises are also sold as different segments. Barcelona is an important stop for us but being the B2B turn around stop may cut into our time at the port. We see online these 2 cruises are also available to be booked as a 23 Day Rome to Southampton and a 16 day Southampton to Fort Lauderdale with Southampton being a overnight stop.  Does anyone have experience revising where the B2B point occurs? Can the existing reservations be adjusted without cancelling and repricing? We booked at a lower price compared to current prices wish to avoid having to reprice.