How to make the PO item number equal to SO item number

Dear Friends,

For the PO item with Account Assignment Category = E, how to make the PO item number equal to SO item number?

Eample:

PO 4700000011 is for SO 7654321. How to make this,

4700000011 / 10 <=> 7654321 / 10

4700000011 / 20 <=> 7654321 / 20

4700000011 / 30 <=> 7654321 / 30

.................

Rgs