You can attach associate existing project files (from same or other projects accessible to you) to the form you are creating if its form settings allow so. Below are the steps to associate an existing project file while creating a new form:

Before proceeding further, remember to ensure that the file you are looking to associate with the form is part of the projects that you have selected in the project filter.

Follow the steps to create a form.

Click on More Options icon at top right side (available based on relevant form settings configuration) to associate docs, aMessages or forms. To associate a file, click on 'Associate Docs' option as seen in below screenshot.

Similarly, the option to associate docs will also be available while replying to a form as shown in below screenshot.

Based on form settings configuration, the option to associate docs can be available while editing an form as well.

A popup will appear wherein files can be selected to associate from the same or other projects accessible to you. Select the files that need to be associated by using the search filters available at the top and then click 'Associate and Close' to proceed further.

In case you need to associate multiple files by navigating to separate folders, use the 'Associate' button to associate selected files in current folder and then navigate to the other folders one by one and associate other files accordingly. Click 'Associate and Close' once done.

The files selected for association will appear at the bottom side.