You mean like one family on one card and another on another card or X,Y and Z on one card and A,B, and C on another? That certainly CAN be done. We do it all the time when we arrive with guests but it MUST be done at the front desk.
{Edit: Sorry. I misunderstood the post. No. The original answer is correct. It cannot be done online, but it most certainly can be done once onsite.}