Hello, Roberta!
We're heading to Walt Disney World as a group of 11, 3 families, and I'm planning on ordering Disney PhotoPass+ at a PhotoPass View Station in the first park we get to, Magic Kingdom. At this time, you cannot pre-purchase PhotoPass + prior to your arrival at Walt Disney World.
However, should you wish to
pre-purchase Disney's PhotoCD prior to your arrival, you can receive a $50 discount by doing so. Then, should you wish to do so, you can upgrade that PhotoCD to PhotoPass+ at view stations throughout Walt Disney World parks, Guest Services at Downtown Disney and select resorts.
Now, regarding your being present at each photo opportunity, just consider that this establishes your PhotoPass
account, not one actual, physical card. Therefore, you can gather as many PhotoPass cards as you need, among all of the members of your party, and later add each of those cards to your account. This way, you'll have access to everyone's photos, all on that one account. Now that's convenient!
Please send additional questions as you think of them; it sounds as if you're going to have a spectacular group visit to Walt Disney World! I'd love to help you gather the most magic possible for all of you!