EMA C++ Configuration Guide : 3 Configuration Groups : 3.1 ConsumerGroup : 3.1.2 Setting a Default Consumer
 
3.1.2 Setting a Default Consumer
If a DefaultConsumer is not specified, then the Enterprise Message API uses the first Consumer component in the ConsumerGroup. However, you can specify a default consumer by including the following parameter on a unique line inside ConsumerGroup but outside ConsumerList.
 
 
<DefaultConsumer value="VALUE"/>