I'm not quite sure how this works, but in the near future, there might be a chance that I might be adding a second sub onto my account.

Currently, I have four characters on my single subscription account. Only two of which I really have much interest in, so only those two I am going to mention right now:

Dhalin (dragon)
Firefur (Saris)

These are currently on one subscription, one account.

A family member has expressed interest in trying the game in the future, and says she wouldn't mind paying for a subscription. If I added this subscription to my account, is it possible I could log on Dhalin and Firefur at the same time?

Or is Dhalin and Firefur considered "one group" while any characters created on the second subscription considered "group two" and only one character from each group could be logged on?

Also, would this give me the ability to purchase a 2nd plot, as long as no character attempts to own two plots at the same time?