Hi - to add to what Ernesto posted, the data will have to be in the main data source of your form to submit or update - so you'll need to copy the data from the secondary data connection into your main data source. You can use the qRules CopyTable or Insert command for this - the important part is that you'll need to be sure to copy in the list item ID from the secondary data source into your main data source and be sure to map the ID field - qRules uses this ID to know whether to add a new item or update an existing item.
Hilary Stoupa
