Despatch Details.

I wanted to create a master list of transporter with following columns
Name, Phone number, Address
and link it with the despatch details in sales/purchase invoice (screen shot attached) for error free entries.

Please help and guide me a with TDL source for same!

 

Searching further, I have found a code as below:

Code:

[#Field: EI PreCarriage]
    Table        : List of Transporter, Not Applicable
    Show Table    : Yes

[Collection: List of Transporter]

    Object    : Tp1, Tp2, Tp1
    Format    : $Name
    Format    : $Phone
    Format    : $Address

    Title    : "List of Transporters"

[Object: Tp1]

    Name    : Transporter 1
    Phone    : 9999999999
    Address    : Address 1

[Object: Tp2]

    Name    : Transporter 2
    Phone    : 9999999999
    Address    : Address 2

[Object: Tp3]

    Name    : Transporter 3
    Phone    : 9999999999
    Address    : Address 3

But is has few issues:

1. Through this I am unable to select a new transporter right from screen and it has to be hard coded
2. No option of blank as Not Applicable is printed if no transporter is selected
3. On editing existing invoices, the transporter detail get deleted if they do not exist on this hard coded table.

Please guide...