Here is a simple script that provides one solution
Names Default To Here( 1 );
dt =
// Open Data Table: Big Class.jmp
// → Data Table( "Big Class" )
Open( "$SAMPLE_DATA/Big Class.jmp" );
theNames = {"KATIE", "TIM"};
theRows = dt << get rows where( dt:name == theNames[1] | dt:name == theNames[2] );
If( N Items( theRows ) == 2,
dt2 = New Table( "Results" );
dt2 << add rows( 1 );
New Column( "Names", character, set each value( theNames[1] || "/" || theNames[2] ) );
New Column( "Height Sum", set each value( Sum( dt:height[theRows] ) ) );
Try( dt2 << delete columns( "Column 1" ) );
);
Jim