It is probably too late for a May 11 cruise. The points go by the billing cycle for the card.
Yes, if you each have an individual RCI Visa then you can apply credits for both cards to the same booking. Actually the award coupons can be transferred. For instance, if Sonny wanted to give me an onboard credit for my upcoming cruise, he can redeem his points and put my name and booking info on the coupon and send it in.