To not make another thread:
How to put together two buildings into one mod properly?
you add a line to your resource file like ...
ExternalList resource
{
External _resources
[
"Template/StorageBarn.rsc",
"Template/StorageCart.rsc",
"Template/StorageYard.rsc",
"Template/CropField.rsc",
"Template/Orchard.rsc:orchard",
"Template/TradingPost.rsc"
"RKEditorChoiceEdition.rsc:RKGardenWallsGreenHouse",
"RKEditorChoiceEdition.rsc:RKGardenWallsStables",
"RKEditorChoiceEdition.rsc:RKGardenWallsWell",
"RKEditorChoiceEdition.rsc:RKGardenWallsFodderFarmers",
"RKEditorChoiceEdition.rsc:RKGardenWallsCustom5Barn",
"RKEditorChoiceEdition.rsc:RKGardenWallsFlorist",
]
}
my example has 12 buildings... you just add lines.