Have Specific Custom Fields based on Variant

-- url of the page with the problem -- : www.solarmade.com/store/product/executive-windmill
-- HikaShop version -- : 2.6.0
-- Joomla version -- : 3.4.8
-- PHP version -- : 5.4.45

Hello,

I am trying to achieve something for our customized products. The products can have custom engravings with 0,1,2 or 3 lines of engraving. Based on the number of lines the customer wants, the price will change. Therefore I have made variants in order to achieve this.

Now for the tricky part. I have made custom fields(text) where people can put in the desired text they would like us to engrave. I am trying to tie the specific custom field(s) to the specific variant but I am finding this hard to achieve. For example: If the customer does not want any engraving I don't want the custom fields to be displayed. If the customer wants one line of text (variant) I only want one custom field to be displayed. If the customer wants two lines of text I want two custom fields to be displayed and so on.

I have attached screen shots so you understand what I mean.

What is the best way to achieve this if I can? Thank you for your assistance.

Thank you Nicolas,

Is there somewhere in the 419 Lines of code I should consider putting the code?

Also I should probably be using the my_custom_function for each of the four different custom fields. Correct!