Hello. Without modification, you can assign a different Dimension to each line. You can create a dimension called line no and assign different line no dimension to each line.
You can also modify CU 90 and add the following line in function
UpdInvPostingBuffer()
//Change this to
//IF InvPostingBuffer[1].Type = InvPostingBuffer[1].Type::"Fixed Asset" THEN BEGIN
//To this line
IF (InvPostingBuffer[1].Type = InvPostingBuffer[1].Type::"Fixed Asset" ) OR
(InvPostingBuffer[1].Type = InvPostingBuffer[1].Type::"G/L Account" ) THEN BEGIN