You cannot carry over your
DDP from POR to your second stay at OKW. You'll need to purchase a separate dining plan for each reservation.
However, if your POR stay is a package and your OKW stay is a DVC booking, then you can purchase tickets to cover up to 10 days with the package and skip buying tickets on the DVC stay, because a DVC reservation does not require a ticket purchase to add a dining plan. You would, however, have two separate dining plans, and on the day you switch resorts you may have to carry two KTTW cards until you use up the credits from the first stay. If your park tickets are on the original card you'd have to carry it anyway, unless you try to get your tickets transferred to your new KTTW card. (You may be able to do that with tickets - but you cannot do it with dining credits.)
I don't know how long you are staying but I think the package tickets only go up to 10 days, so you might have to buy more tickets anyway if you are staying longer than that.