Adding a Data Set to a Concatenation

To add a data set to a group of data sets concatenated to a ddname, either:

Reallocate the entire concatenation including the data set to be added using the ALLOCATE command, and specify the REUSE operand.
Use the FREE command to free the data sets in the concatenation. Then reallocate the entire concatenation, including the data set to be added, using the ALLOCATE command.