Krystal Enchantment

I'm hoping to get some help in understanding how two premium accounts can use their allotted free 1024 M2 on one piece of land. I have read in some research about using a group to do this. I was wondering how it would actually work. I'm interested in purchasing a 4096 M2 land, once I purchase this and deed it to a group which include two premium accounts, will it register that and I would only have to pay the monthly fees for the remaining 2048 M2 between two accounts? Or exactly how does it work? Any help is greatly appreciated.