Hi,
There are others with much more knowledge/experience who I am sure will reply, but here is my take. You basically have 3 options to do what you're thinking of.
1. Buy one huge contract with everyone's name on the title.
Advantages: don't have to worry about transferring points or linking reservations, it's all one contract and one membership. You can maximize the use of points and minimize the chances of wasting points. Also, large contracts will usually have a cheaper $/point cost if you're buying resale.
Disadvantages: You all have ownership of the same thing. A contract can NOT be split (i.e. a 200 point contract can not become 2 100 point contracts).
2. Buy the same contract (same # of points, same Home Resort, same Use Year) for each person and title them all the same (so everyone still owns each contract). So if there are 3 of you, you may buy 3 50-point contracts at Animal Kingdom Villas with a February Use-Year. To be sure, they do not all have to have the same number of points.
Advantages: If they are the same HR, UY and same people on the title, they can be combined into a single member number (but still distinct contracts), so they act like one big pot for booking rooms. This also allows one person to get a larger contract if they also want to use it for other vacations (have 2 50-point and 1 100-point contract), but they MUST be the same UY, HR and titled the same (everyone's name on every contract!!). Another advantage is that if you decide later that the "together" thing doesn't work, you can re-title the individual contracts and you will each own your own part.
Disadvantages: You are paying to close/title multiple contracts. This is also more difficult to do if you choose resale because you might not find all of the right contracts at the same time, so it might take a little more work/time. Also, the smaller contracts will have a higher $/point if you're buying resale.
3. Have each person buy their own contract (whatever they want and title it however they want). Then each person can make reservations for a part of the vacation (so maybe have a Mon-THursday reservation and then a Thursday-Sunday reservation) and then link these reservations (if it's for the same rooms at the same resort) so then it's one continuous vacation but you each "purchased" a different part of it.
You could also transfer points into a single contract in this case, there are problems though. You man only transfer in/out of a membership ONCE per UY. So you could do this with 2 contracts, but not more, because once you transfer from membership B to membership A, you can't transfer from membership C because membership A has already used up their transfer! Also, if there are different home resorts or use years, these are retained when you transfer the points so you may find booking what you want difficult.
Advantages: Each person owns their own contract.
Disadvantages: Logistically a nightmare. ("what? I thought YOU were supposed to book Thursday!") ("Yeah! I got the reservation!", "Oh, I forgot to look at 8:00 and the Standard view wasn't available for the other dates. sorry...") ("Why do _I_ have to buy the weekend, it is more points!!!").
Just my $0.02
