Working on Adobe Form to produce a PO - Need Text Fields to appear only when triggered

Hi everyone, 

I am working on a PO Form in Adobe Acrobat. 
The PO needs to have multiple text area rows based on Item Number/Description/Qty/Uom/Cost/Total.

I was able to get the Total to calculate when Qty and Cost are entered, and produce a final Total with Qty x Cost + Freight (if applied). That's great—however, the Uom (unit of measurment = EA for every line) and Total ($ 0.00) appear in each row whether the user has an Item Number entered or not, which I don't want.

I only want the auto-populated Uom (EA) and Total ($ 0.00) for that row to appear if the user enters an Item Number. Sequences as follows:

Item Number (triggered) > Uom = EA will appear (EA = Default Value under 'Options')
Qty (entered) and Cost (entered) > Total = $ 0.00 will appear based on (Qty x Cost)

I will include images for reference—I hope they help! If anyone can assist, I would be very thankful. My guess is that I will need to use some kind of Script to accomplish this.