help me to resolve through groovy

[Oduvil Jayachandran]

I have a EDI file with me like this

:

S5*1*CL~

N1*SF*GENERAL MILLS~

N3*1370 ORCHARD RD.~

N4*MONTGOMERY*IL*60538~

S5*1*CL~

N1*SF*GENERAL MILLS~

N3*1370 ORCHARD RD.~

N4*MONTGOMERY*IL*60538~

S5*1*CL~  ------------------------------to be changed into S5*1*BL

N1*SF*GENERAL MILLS~

N3*1370 ORCHARD RD.~

N4*MONTGOMERY*IL*60538~

S5*2*CU~

N1*ST*GENERAL MILLS OPERATIONS, LLC~

N3*6055 S 6TH ST~

N4*Milwaukee*WI*532215119~

S5*3*CU~---------------------------------to be changed into S5*1*DL

N1*ST*WAL-MART  6025~

N3*6140  3M DRIVE~

N4*Menomonie*WI*54751~

Above text contains set of status (highlighted) loops which can be increase or decrease. 

I would like to change the last set of CL loop will be changed into BL and last set of CU loop will be changed into DL.

Possiblities of in single loop as well so their status must be BL and DL respectively.