There is a sample of this in samples/datapage/LabelOnLeft.model (and its sister, LabelAbove.model). In those samples, the Phone Number table is what you are looking for. If that sample is not currently in your WPF project, then you will need to add the "Building Models" feature set to the project.
The steps include:
- Put a Data Column Modifier on the table and choose a delete column style. If you want to manage deletes yourself (or not allow them), then you can choose "No Column but generate Remove/Add methods." Any of these choices except "No Delete Column" will cause a method to be created ElementName_Add.
- Put a button or a link on the page which calls the _Add method. If you are using the default HTML Templates to create the page, then there will be a convenient place to put that button -- ElementName_ButtonSpace. In the Button or Link Builder, in the advanced section, choose "Rendering Mode: Render Outermost page after running action." (This is because the _Add method doesn't result in a page to display. Another approach would be to create an action list that calls the _Add method and then shows the page, and then have your button call that action list. You might do this if you have some other step that needs to be performed, such as initializing some of the data.
Note that there will initially be nothing in the table if your data is empty. You might want to call the ElementName_Add method yourself before the page is first displayed so that there will be a blank row.
PageAutomation will handle collecting the data correctly and putting it back into the variable that your table is based on. This even works if the table is paged, though you have to make sure you let PageAutomation invoke the PagingAssistant builder. That is, you must turn on paging with a Data Column Modifier or a Data Field Modifier, don't invoke the PagingAssistant yourself.
If you just want the user to be able to provide a single value for this input in the form, then you'll need to tell page automation to adjust the schema. This can be done by adding a Data Field Modifier builder to the model and pointing it at the unbounded element in your schema. You can then set the Element is Repeated input to No and the Promote Children input to Yes. This will provide you with a single input field for this schema element.
If you want the user to be able to provide multiple values for this element, as the schema allows, then you need to add some additional functions to the input page to support this.