I am so glad you asked as there are several tools built into Workingfarm that allow selling a box program easy. 

Option 1

Add Specific Box Programs as Customers

1. Go to the Customers tab under Orders.
2.  Add a generic customer for all your box products. For example you could create a customer called Small Box Program, Medium Box Program and Large Box Program if you offer boxes with different quantities.

Select Weekly Box Program Product Items

1. Each week create new order for by Box Program to add the specific items available for that box.
2. Go to Orders tab and click on + Order button, select the box program you are creating with list of product items. 
3. Click on + Products to get the Product Order page and select the items to include in this weeks box then click the Add button.
4. The items will be listed in the Customer Order window with the estimated price for the items. Use this feature to build the box which is close to the total flat rate value you want to charge for the box. Delete and add products until it matches your requirements. Take note of the specific Order Number as it will be used in the next step.

Add Weekly Box Program Order to Box Program Product 

1. Go to Products tab and create a new product for each of these box value. Click on the + Product button, Set the Product Type to “Box Program”. If you have already done this step then click on the edit icon from the product list. This will display the Box Order Number field. Click on the Order Number button to display list of all orders.Select the order number from Step 4 above.
2. Go back to the Orders tab and + Order for all customers that are part of the box program. 
3.  Using the + Products button, select the box program and enter quantity of 1 then click Add button.
4. The Order page will list all individual items as well as the Box Program item. The estimated value will add all items to the total. 
5. On the Packing day, go to the Packing tab and select Customer List from the View List options. 
6. As you are packing each box item for a customer, select the Complete flag as it is packed. DO NOT ENTER A QUANTITY. Only the Box Program itself will have a Quantity of 1 and Complete selected. 
7. Click on the Invoice tab and click on the Invoice for any of these customers whose order is completely packed. You will see that only the Box Program item has a value.
8. Fill in the Payment information as you recieve payment. 

Option 2 

Duplicating an Order and Changing Customer Name

1. Follow all the steps above down to "Add Weekly Box Program Order to Box Program Product - Step 2". Instead of adding a new order for each customer on the Orders tab, you can create one and then duplicate for the other customers. 
2. Once you have duplicated an order on the Orders tab, click on the duplicated order to open the Order Details window. 
3. Edit the customer name to select another in the box program. 
4.  Repeat this until you have an order for every customer in the program.