Here is a simple way to show a few form fields based on Checkbox:

1. Add your fields, name them like group_name_1, group_phone_1: https://snipboard.io/IBOcMn.jpg

2. Hide them Via CSS (will hide all fields named group_*)

[class*="fv-field-key--group_"] { display: none; }

3. Oo click to the checkbox – show them via JS:

jQuery(".fv-field-key--is_group_checkbox").on("click", functin() {   jQuery(".fv_upload_form").find('[class*="fv-field-key--group_"]').show();
});

The checkbox should have the name “is_group_checkbox” or change in JS, ex: https://snipboard.io/IBOcMn.jpg

CSS ad JS could be added to the plugin’s settingsю