Invoice from InvLineItems

I am having great difficulty creating a working relationship between my InvLineItems and Invoice files as I have a unique set of fields that I am working with.

I ship various products via truck from various suppliers and it is all organized via my "Orders" file. As the load is shipped, I enter the shipped weight in "Orders" and a "InvoiceLineItems" record is created. I need to get the info from InvLineItems to my Invoice.

My "InvoiceLineItems" entries are created from my Orders file via a relationship defined through a "ShipSerial" field that is unique to each order.

My "InvoiceLineItems" has the following pertinent fields:

ShipSerial (key in InvLineItems to Orders relationship)

LoadSerial (unique serial number, cannot modify)

ShipWeight

TruckName

LoadB/LNo

InvoiceNo

My Invoice file has the following fields:

InvoiceNo (key field to InvLineItems)

ShipSerial (key to Orders) - not sure I need this one

LoadSerial (another key to InvLineItems)

The only time that I can get these all to work is when I check the "Also Delete Related Record" and the 'Allow creation of related record" in edit relationships box. I do not want to delete or add - I just need to bring forward.

I hope that I am making myself clear but let me know if any more explanation is needed.