Hi Joseph. Welcome to the forum.
You want to check the drop down lists when the user clicks the button. I think the issue is the stock (default) button you receive with the form.
Typically you would just add some rules to the button. Open the properties of the button and switch it from a query button to a rules button with the dropdown. Then you can do all the checks and logic you want. At the end once all of the validation has occured add a rule to Query your main connection.
Another method is to add a field to your form which holds the validation status. You mayneed this external field to store your validation progress. Then on your query rule you can use the confition flag = foo and then the Query would run.
Hope this helps.
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