The OP is correct...when you book a package the dining is tied to the room reservation...the number of dining days corresponds to the number of room nights. You must purchase MYW tickets to get the dining, but the tickets can be for any number of days...in this case they have room and dining for 5 nights and tickets for 8 days. and a seperate room only reservation for 2 nights
We booked a package with dining also for 5 nights and only bought 1 day park passes (we had left over days on assorted old park hoppers for the rest of the trip)...5 night room, 5 days dining, 1 day park passes.
You cannot carry over meal credits however to your last day...they will most definately expire on midnight of the day your package reservation ends...sad but true....you might want to move your Universal day to keep from wasting those credits!! They will however be happy for you to stay in the same rooms...IF you let them know when you check in that there are 2 reservations...and I would also suggest stopping by the front desk the day BEFORE your first reservation ends to remind them...you will most likely still have to come by the desk and get new keys, leave CC again etc...but if they have warning they won't make you move.