I think the way it has been done in the past has worked well. ....Most recently with LA and earlier with other sims.
We have had the chancellor take a list of names of current citizens who desired specific parcels. When the sim was opened, the parcel is set for sale to the current citizen who asked for the parcel. If there is more than one person asking for certain properties then that has to be dealt with fairly of course, and hopefully openly. The rest of the land would then be put on the open market. First come first serve. We are limited in how many parcels any of us own at any one time ( hopefully this is fully enforced ) and so, thankfully, no one person can go buy the entire sim or go over their 8 parcel limit. If the land is bought up so quickly that there is a waiting list after that .. well.. perhaps we go buy another sim really quickly, but honestly I think one sim will do us just fine.
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another thought:
As I keep whispering, the way to make our five , hopefully soon to be six sims go further is to lower the number of parcels each of us can hold at any given time. Imagine how many more active citizens we could have ! For no more financial risk. Granted, it would take a bit more time to manage things, but we should also have more volunteers and more people to do the work ! It would be a gradual increase (not like the instant one with the AA merger) All we have to do is did cut the number of parcels a person can hold .... I would suggest we do it by attrition. As far as I know only one person is currently technically imho is over the 8 parcel limit.( 0wning 8 parcels as an individual and some as a group). Anyone over a new limit we could set, lets say we make it 4 parcels, could not buy land and hold it for a person .. like pat did for rosie because it would technically be against the law. I would want there to be an exception made also to grandfather people in, lets say they own 6 now and we make the new rule 4... we can grandfather in the 6, but when they sell two or one they cannot replace the land. They have to keep to 4 after the two are sold or abandoned.
The truth isn't that we need to expand only because people want more land, I honestly think CDS NEEDS more active participating citizens in order for the government to work in a healthy way with no overlaps of power and duties. The EMs should not be part of the executive team and sit on the RA and in the SC at the same time imho for example. We need MORE people to do events and run meetings, and more to help with hippo. And build and be in the guild, more not less.... More people NEED to be involved. We need more volunteers to work in the government positions we have set up.. more for events and jobs.. Buying a new sim is ONE way to do that. I want to do that, too ! Lowering the number of parcels any one citizen can own, well, it also is a way of increasing the population... AND it can stop people from "holding land" so no one else can buy it too, if this number of parcels is enforced.