System bifurcated revenue on line item basis for different material in invo

Hi Friends

When i reaised a invoice for three material system showing three line item for the revenue in accounting document. Where revenue G/L is the same. As per my client requirement he want all revenue must posted in one line item in accounting document.

e.g line item -

---

posting key--

---

G/L--

---

amount

1--

---

01 (Customer)

---

XXXXXXXX--

---

6000

2--

---

50 (Revenue)--

---

ABCDEF -3000

3 50 (Revenue) ABCDEF -2000

4 50 (Revenue) ABCDEF -1000

Where as per requirement it must post to accounting document

line item posting key G/L amount

1 01 (Customer) XXXXXXXX 6000

2 50 (Revenue) ABCDEF -6000

Please help me to solve me the issue.

Regards

Shambhu Sarkar