Etihad is the only airline I know where you can do two one-ways and charge half the return fare of each way - I recently did KTM-XAUH-NRT-XAUH-DEL, which is half the return fare of KTM-NRT and NRT-DEL each. Sorry, not that I'm helping the topic...

However, not sure if you can do BRU-MAA-SEZ-JNB as that'll be 3 routes - you can do BRU-XAUH-MAA-XAUH-SEZ and purchase separate ticket for SEZ-JNB, or BRU-XAUH-MAA/SEZ-XAUH-JNB and purchase separate ticket for MAA-SEZ.