Multiple quotes and answers:
This may be a pricier option, but if you really want to stay on property with Granny, it will work. You have to buy a minimum oe day ticket for the room promo. Buy everyone in the room a one day ticket. Then, buy tickets throgh another source for the rest of the party for the days they want to go to the park.
No need to purchase separate tickets. Once everyone is checked in and has their one-day tickets, you can upgrade anyone's ticket that needs more than that. You sinply pay the price difference between a 1-day ticket and the ticket you want to have. This can be done at the Lobby Concierge, park ticket window or park Guest Relations.
However, I have a question for you. What if everyone wants to eat in a park? How will Granny go? You may want to explain to her the tickets would be great for dinners in the parks and that she doesn't have to go all day.
This is another good idea, though the OP did mention that it was a matter of cost.
Some friends and I went down for 7 nights in September. We wanted to have a relaxing trip, and a couple of my friends weren't planning on going to a park every day that week, maybe only 4. But we still got them 7-day tickets because there were a couple times that we wanted to go into a park to eat dinner, maybe catch fireworks or a couple of favorite attractions. (For example, on our arrival day, we went to Epcot early evening to ride Spaceship Earth, have dinner at Le Cellier, and watch Illuminations)
I have some questions about staying on property with two different reservations.
1. Will we be able to use the 9 day ticket from the first week of our trip during the second week of our trip? I know tickets are good for 14 days from first use, but I just want to make sure my plan will work.
Yes, the tickets on your first room key will still be good beyond the first reservation's check-out date. They'll be good until 14 days after they're first used. (The ticket and hotel portions of the key card are entirely separate and aren't linked)
One thing to consider would be to upgrade the first reservation to 10-day tickets rather than 9, and then don't use the 1-day tickets on the second reservation at all. For one extra day, it's only about $3 per person on the first ticket. But that 1-day ticket on the second reservation is worth $75 per person. It'd be a waste to use them. Much better value to not use them at all and keep them for a future trip, at which time you can upgrade those 1-day tickets to what you need then.
2. Do we have to go check out and then check in on the 20th?
3. Will we be able to stay in our room (like hang out some during the day) on the 20th even though that is our check in / check out day?
4. Will we have one key to the world with both reservations on it, or will we have two because we technically have two reservations? If we have two keys (one for each reservation), will our tickets from the first week still be active on that card after the first reservation ends?
On your "change-over" day, you will have to visit the Front Desk. They will check you out of your first reservation, settle up any charges on your room charge, and then check you in on the second. They'll issue you new keys, because each set of keys is linked to a specific reservation, with set dates printed on them.
When you check in for the first reservation, make sure to remind the desk that you have a "continuing reservation" and would like to stay in the same room. 99 times out of 100 they'll be able to accommodate you.
If you're in the same room, there would be no need to vacate it during the day, other than for your usual housekeeping visit.
The one down-side is that if you follow the ticket suggestions above, during your second week each person will have to juggle two key cards. The one for the second reservation will get you into the room (and will be the one you need to show for Extra Magic Hours, etc), but the one from the first week will have your park tickets on them and will need to be used for park entrances and FastPasses. And you really have to be careful, because if you accidentally put Week 2's card in the turnstile one morning, *poof*...there goes that 1-day ticket.
Normally, they could move tickets over from one key to another, but your second room keys will have those 1-day tickets that you won't be using.
There *is* one possibility, though I'm not sure whether the Front Desk or a theme park Guest Relations would be better to do this:
They can "strip" a ticket off of a room key and issue it on its own separate ticket media. (I believe Disney's term for this in "unlinking" the ticket from the reservation) I presume after that's done, it leaves the room key available to add another ticket to it. So, they could take those not-to-be-used 1-day tickets *off* Week 2's cards, give those tickets to you separately so you can safely hide them away, and then move the tickets from Week 1's cards to Week 2's.
I suggest going to the Front Desk and explaining exactly what you'd like them to do, and see what they say. The worst-case is that you're juggling two sets of keys for Week 2.
Whew! Did that answer everything?
-Rob