There is a very useful extra statutory concession which enables land that is owned by two or more individuals to be sub divided so that each person ends up owning their own share of the land. The concession is extended to various lands that are exchanged. There are problems with the exchange of dwelling houses.
The concession does mean that it is possible to do the exchange without any payment of capital gains tax and since the land is in effect partitioned avoid stamp duty land tax. Without the concession, capital gains tax would be payable by both parties on the disposal of the land.