Adding a required setup fee to ea subscription

Hi Stack Ideas,

2 things ....

Please help me understand where to add in a required part to the pay plans subscription whereby ea paying member pays an initial introductory one-time fee. This is a required part not an addon. You can go to the site and see the front where I have them listed and the bottom of ea shows the intro fee info..... Just need to make it mandatory.

And, then if they upgrade, we want to apply what they've already paid in intro fees from previous level to the next level's intro fee.

Here is our sandbox: https://50.28.37.1/~circleofbeautifu/apply-for-membership

Thank you!
Deidre