This is a slightly improved version of an old tutorial of mine.
There is another technique, used quite often by Maxis, that can be used to achieve a very similar effect to prop families. I have not seen any obvious mention of it, and I thought that it would be worthwhile to make the community aware of it.
Like prop families, it requires simple modding. In this technique the lots are modded, not the props. No new prop family ID’s are needed.
The goal is to have a different prop show up each time the lot is plopped. The props that can show up are specified in a list of prop instance ID’s (or prop family ID’s).
The first task is to find the instance ID’s of all the props that will be in the list. One way to do this is the use the Lot Editor. The Lot Editor displays a prop’s instance ID when you select it to be placed on the lot.
The next task is to use the lot editor to take the first prop in the list and place it on the lot. All the props will show up in this position. Save the lot and exit the Lot Editor.
Now you need to mod the lot…
In Reader, open the .SC4LOT file created by the Lot Editor in the previous step. Find the Lot Exemplar of the lot you just saved (The exemplar type is LotConfigurations).
You need to find the LotConfigPropertyLotObject for the new prop (the prop you just added with the Lot Editor).
Look for the last LotConfigPropertyLotObject line with a value of 1 as the first rep and check to see if the value of rep 13 is the new prop’s instance ID. If this LotConfigPropertyLotObject line does not have the correct value in rep 13, you must check all the other LotConfigPropertyLotObject lines that have a value of 1 as the first rep.
The LotConfigPropertyLotObject line you found above already has the first prop instance ID as rep 13. Create the list by adding, to the LotConfigPropertyLotObject, new reps 14,15,16,…. with the values of additional prop instance ID’s. For example, if you had 10 items in the list, you would now have 22 reps.
Do a Reindex LotConfig for good luck, and save the .SC4LOT file. That’s it!