This command changes the owner of the specified province and also makes it a core of the country with the specified country tag.
own_core [province id] [country tag]
|Province ID||The ID of the province you wish to change the owner of and also make a core.|
|Country Tag||The country tag of the country you wish to make the owner of the province.|
Central Australia has a province ID of 1791. This command would make the nation you are currently playing as the owner of Central Australia and also make it a core.
own_core 1791 DAN
The above command would make Denmark (DAN) the owner of the province with ID 1791 (Central Australia) and also make it a core.