Hello, Nancy!
You can only have one main PhotoPass + account, but you can add multiple PhotoPasses to that same account, so if you split up, you can still have all of your PhotoPass photos added to your PhotoPass + account simply by adding the code on the back of the PhotoPasses to your account.
That being said, what will be tricky is the attraction photos. You'll need to have the PhotoPass + with you in order to add those. However, last month, my husband was able to get a Cast Member to write down the code # of an attraction photo which was taken of 1/2 of my family while I was at Blizzard Beach with the other 1/2...and the PhotoPass +. That code, he was told, could be taken to a viewing station, where a Cast Member could pull up the photo and add it to our account. At a different attraction, he was told that that is not an option. As such, those additional attraction photos will be trickier to get onto your account, if you can do so at all.
In the end, it might be better for you to have at least two PhotoPass + cards so that the likelihood of having at least one card in the split-up group will be higher.
Nevertheless, we really liked having the PhotoPass + card with us, as we were more likely to stop for photo opportunities and, as such, have some really wonderful professional-quality pics we'd never have otherwise. The large group shots in front of park icons alone made it worth the price.
If you decide to purchase the Disney PhotoPass +, don't forget to take advantage of the
pre-order discount, which brings the cost down to $169.95, making this an even better deal for great photographs from your trip to WDW!
Send more questions as you think of them; I'd love to help!