Opening a dialog from a form instantly submits the form

[leeoocca]

I have the following use-case:

1. User can select from a list of options
2. If the option they want doesn't exist, they can create a new one.
3. As the options live in a separate table, I prefer to separate the forms. Since I already have another form on the page, I create the second form in a Dialog.
4. Problem: every time the dialog opens, the form is submitted. I can only see the dialog if there's an error in the form.

I'm using Formsnap and the Dialog element.

I know that per HTML specification we can't have nested forms. Theoretically this shouldn't happen as the form lives in the portal.

Did anyone have a similar case? How did you solve it?