You can try doing both reservations online, but during the 180 + 10 period you have to sign into your resort res to take advantage of the +10 so it will probably be easier to call and let the dining line CM do them.
Once you're within the 180 days anyone can make dining reservations - onsite guests, offsite guests, locals - so you won't have to link your resort res. At that time you can make both reservations, but you will still have to use 2 different names and phone numbers.