I have a form Called "Contracts"

that have the n° of contract,  quantity , client.

exemple: contract n°1  , quantity: 200, John.....

a contract is delivered in parts 

contract 1,  delivery 1, quantity: 152 in november

                 delivery 2, quantity:  048 in december.

I Want to People view All Contracts and them add a Delivery order.

--------

I Was trying like this:

Made a form called "contracts" with contracts info.

Made a form called "Delivery" with delivery info.

Made a middle form called "add Deliverys" with one look up for contracts, and multiple look up for deliverys with allowed new entries. 

Now i think that to this work, i need add a button on "contracts view" that opens "add deliverys".

1)how can i do this?

2)there is another way ?

thanks.