Concat Column2 data in one record based on column1 through JCL

I have a file having parent and child data in column1 and column2 respectively. I have a requirement to concat all the child from same parent in one record. How can we achive this through JCL ?

Expected Result shoold be like this : Input file :

Parent    |Child  
ABCDEFAAAA|1233444111  
ABCWEEAAAA|3456544111  
ABCDEFAAAA|3435677111  
HFFDDDAAAA|6444554111  
ABCDEFAAAA|2424234111  
HFFDDDAAAA|4334456111  

Output should be like this

Parent    |Child  
ABCDEFAAAA|1233444111,3435677111,2424234111  
ABCWEEAAAA|3456544111  
HFFDDDAAAA|6444554111,4334456111  

As Martin packer pointed out, it can be done in a single pass of data and get the desired results. Here is a sample which can handle upto 99 children per parent, but only the first 10 are handled as OP mentioned that the max is only 8.

//STEP0100 EXEC PGM=SORT                       
//SYSOUT   DD SYSOUT=*                         
//SORTIN   DD *                                
ABCDEFAAAA|1233444111                          
ABCWEEAAAA|3456544111                          
ABCDEFAAAA|3435677111                          
HFFDDDAAAA|6444554111                          
ABCDEFAAAA|2424234111                          
HFFDDDAAAA|4334456111                          
//SORTOUT  DD SYSOUT=*                         
//SYSIN    DD *                                
  SORT FIELDS=(01,10,CH,A),EQUALS              
                                               
  OUTREC IFTHEN=(WHEN=GROUP,                   
             KEYBEGIN=(001,10),                
                 PUSH=(081:ID=8,               
                       090:SEQ=2)),            
                                               
         IFTHEN=(WHEN=GROUP,                   
                BEGIN=(090,2,ZD,EQ,01),        
                 PUSH=(094:12,10)),            
                                               
         IFTHEN=(WHEN=GROUP,                   
                BEGIN=(090,2,ZD,EQ,02),        
                  END=(090,2,ZD,EQ,01),        
                 PUSH=(105:12,10)),            
                                               
         IFTHEN=(WHEN=GROUP,                   
                BEGIN=(090,2,ZD,EQ,03),        
                  END=(090,2,ZD,EQ,01),        
                 PUSH=(116:12,10)),            
                                               
         IFTHEN=(WHEN=GROUP,                   
                BEGIN=(090,2,ZD,EQ,04),        
                  END=(090,2,ZD,EQ,01),        
                 PUSH=(127:12,10)),            
                                               
         IFTHEN=(WHEN=GROUP,                   
                BEGIN=(090,2,ZD,EQ,05),        
                  END=(090,2,ZD,EQ,01),        
                 PUSH=(138:12,10)),            

         IFTHEN=(WHEN=GROUP,                                         
                BEGIN=(090,2,ZD,EQ,06),                              
                  END=(090,2,ZD,EQ,01),                              
                 PUSH=(149:12,10)),                                  
                                                                     
         IFTHEN=(WHEN=GROUP,                                         
                BEGIN=(090,2,ZD,EQ,07),                              
                  END=(090,2,ZD,EQ,01),                              
                 PUSH=(160:12,10)),                                  
                                                                     
         IFTHEN=(WHEN=GROUP,                                         
                BEGIN=(090,2,ZD,EQ,08),                              
                  END=(090,2,ZD,EQ,01),                              
                 PUSH=(171:12,10)),                                  
                                                                     
         IFTHEN=(WHEN=GROUP,                                         
                BEGIN=(090,2,ZD,EQ,09),                              
                  END=(090,2,ZD,EQ,01),                              
                 PUSH=(182:12,10)),                                  
                                                                     
         IFTHEN=(WHEN=GROUP,                                         
                BEGIN=(090,2,ZD,EQ,10),                              
                  END=(090,2,ZD,EQ,01),                              
                 PUSH=(193:12,10)),                                  
                                                                     
         IFTHEN=(WHEN=(090,2,ZD,EQ,01),                              
              OVERLAY=(105:99X)),                                    
                                                                     
         IFTHEN=(WHEN=NONE,                                          
              OVERLAY=(094:94,110,SQZ=(SHIFT=LEFT,MID=C',')))        
                                                 
  OUTFIL REMOVECC,NODETAIL,                                          
  SECTIONS=(81,8,                                                    
  TRAILER3=(01,12,94,110))                                           
/* 

The output of this is

ABCDEFAAAA|21233444111,3435677111,2424234111       
ABCWEEAAAA|33456544111                             
HFFDDDAAAA|46444554111,4334456111