You must be talking about a special ticket because FL residents can purchase a 10 day ticket just like anyone else can.
I'm guessing the OP is referencing the discounted Florida Resident Disney Select tickets.
I see that the maximum number of days ticket for a FL resident is 4 day tickets. If I need 5 days....Can I buy the 4 day tickets then upgrade the extra day for a nominal fee ($20) or would it be like starting from scratch with a new one day tickets (more like $115). I realize I won’t have pre-booked fastpasses availability on that 5th day.
Assuming my above guess is correct and you are referencing the discounted Florida Resident Disney Select tickets, no, you wouldn't be able to add a 5th day at the discount. Those tickets come in 3 days and 4 days. A 5-day ticket would be at the tourist price.
Your options at current prices, AKA before October 16:
- a FL 4-day ticket ($243.89) + An additional 1-day ticket ($121.41 for a regular season, no-MK day) = $364.80, adjust as necessary if the ticket would be used at MK or on a Peak or Value season day
- a tourist-priced 5-day ticket, must be used up within 14 days of the first use = $420.68
- two FL 3-day tickets = $445.18, gives you an additional day to use within the ticket's 6 months expiration period
- a Florida Resident Silver Pass (if the blockout dates are acceptable for your use) = $467.54 with the ability to pay $28 and change monthly, includes parking for the whole year
Please note that I've used base tickets for these price comparisons (no Park Hopper).