I'm sure you could, but ask Annette or Margaret at Harbor Ridge at 866-384-0231. Both are great to work with.
can this be added to one's individual II account? (so don't have to pay for two membership fees?)
It all depends on the affiliation agreement that your other resort has with Interval International. For example, if you are a Hyatt resort owner, then a second II membership would be required. In general, if your Interval membership is included in your resort's maintenance fee, then you would be required to get a second membership.