Thanks to a great question from Scott with paddletsra.org, Here is a tutorial on using the build from one custom form tool as a foundation for a new one!
If you make a lot of use of the Form Tool, You may have an already complete form that you would like to just make a few small changes to as a new form for your website. Here's how you can save some time and easily use and existing form as a jumping off point!
Go to your site builder and add a new form tool. Once you have it added, go to the "Edit Form Fields" tab and choose to "Inset a new element from another tool"
Once this is chosen, click on "Add and Edit" and it will bring up a window that looks like this:
Here, there is a drop down menu where you can pick which existing tool (existing form) you would like to copy to start your new one! It will pull the existing form's build into your new form without deleting or changing the previous one.