Relationship, Link, Autofill????

Part of the database that I have written prints out consignment notes for the waste management industry. The consignment note comes on two parts Part A Company details, producer details, waste details, Transport details. Part A has 150 fields and selects some information via combo boxes from other tables (legislation codes ect.)
Part B only contains wastestream information. This form has 95 fields again pulling information from other tables via combo boxes.
The two forms are nothing alike so I use two printers
The database works without any relationships or links.
The Problem:
Together the two forms allow for 11 lines of information to be stored and printed .Part A generates the consignment number and allows for 2 lines of information. To enter the remaining 9 lines of information I use a command button to ask the user to enter the consignment note number to call up the blank part B form.
I am now wanting to store more than 11 lines of information
Because of field limitations I have had to replicate the Part B form in a table of its own. When the additional form is called 3 fields are autofilled.
What I want to do is because there can be 1 line of information or 20 lines of information I need these 3 fields always to be synchronised so as the information is keyed into Part A , it autofills into the other table .
You can't get to part B without filling in Part A, but part B or the copy for the additional lines may not be needed every time but I need it to enter the data accross in the simplest possible way.

Dave