Yes, you can! We did this for a family trip and it worked out great. We split the $99 cost amongst all 4 families so it was very reasonable.
Create ONE photopass account and preorder the disc from that account. Give everyone in your family the account info (login and password) and have everyone import their photopass cards into that one account. OR, have everyone give you their photopass cards at the end of the trip and you import them. You can import as many photopass cards as you end up with - we kept forgetting ours at the room and ended up getting a new one almost every day while my brother, being the organized one, only had the one photopass card.
If anyone logs their photopass cards into another account, you CAN'T move it to the group account and those pictures will not be included on the disc.
After the trip, have everyone review their pictures and make any edits (add backgrounds, etc.). Set a deadline for about 2 weeks before the pictures expire to keep any stragglers in line! Once everyone is done, order the disc. The credit will come up in your cart when you order it so it will show a $0 cost.
It will arrive in about 2 weeks (at least that's how long ours took) and you can then make copies to pass along to family members. A copyright release is included on the disc as you are buying all rights to the pictures - some places will ask to see this when you print the pictures (
Walmart can be a stickler for this).