How to shift specific cells using Apache POI?

Question

Hi,

My excel sheet contains different regions on the same sheet like :

region1:             region2:
John       2             A       1
John       1             B       2
Sue       1             C       3
Sue       2             D       4
Alice       5             E       5
Bob       1             F       6

I want to add new items into one of these regions without affecting the other regions. I tried using rowShift() method but it is also deleting the complete rows. Is there any way that can shift the specific cells down and can insert rows into the specific regions like : In my given example i want to add one more row in region1(also retaining all old rows) and it will become :

region1:             region2:
newval       newval             A       1
John       1             B       2
Sue       1             C       3
Sue       2             D       4
Alice       5             E       5
Bob       1             F       6

Thanks in advance.