Dennis @ PerfectForms
If I have a table in a parent from which I am extracting custom parameters, I like to use a helper field to temporarily hold that value (in your case, the email address). You can make it a hidden field if you want.
When you start the behavior use a set table object to move the current row of the table to the first row. Then set your new field with the value in the current row of the table, then bring in your show form object to create your child (using the value in the new field as your custom parameter). From here you need to create a looping behavior to make sure that you create a child for every row in your table. Use a set table row and move the current row to the next row. Then use a simple branch with the advanced condition (special – last command was successful). If true, loop back to your set field. If false, end the behavior. This behavior will launch a child instance for every row in the table.
I will add another bit of advice: If you want the child to simply open, grab the custom parameter, close, and send a notification, use a hidden helper field in the child. Create a behavior on when the form opens. Start with a simple branch – is the hidden field empty? If true, then set the hidden field with a 1 (or any other value), set the email field with the custom parameter, and submit the form (closing the browser window). When the user clicks the link in the notification to access their form instance there will be a value in the hidden field so the instance will remain open for them!