Help transferring SQF Source values around site URL

Site URL: https://www.fabupack.com

Been trying to figure out how to transfer a SQF parameter tracking link from my site's landing page (Home Page) to the eventual drop off page (Contact Us) to record the source using SQF_SOURCE in the Squarespace Form. 

Here is the typical user flow: 

1. Ads send to (Home Page)  http://www.fabupack.com/?SQF_SOURCE=Google
2. User likes what they see and would like to contact us, clicks on 'Contact Us' on the site's nav bar and gets redirected to (Contact page) http://www.fabupack.com/contact     (tracking is lost!)
3. The '?SQF_SOURCE=Google' disappears, and I cannot attribute the source in the contact form submission. 
4. Goal is to achieve ' http://www.fabupack.com/contact/?SQF_SOURCE=Google' and carry the SQF_SOURCE value when the visitor basically jumps around the website and eventually submits the contact form. 

I have a feeling the solution might be in the form of a script but please experts, I need your help! Surely others have experienced this complication. 

I would prefer to record them directly via SQF instead of using a UTM/GA workaround. 

Much appreciated. Thank you. 

 

I'm having the exact same problem here. Any help?
@bchambraud I'm wanting to do the same as you but with utm tracking so that the data records into Google Analytics too. Could you share your workaround with me?