InfoPath Dev

I have a repeating table with two columns - "projects" and "sections". In these columns I have drop-down listbox, that has a form data source. The idea is to update the "sectionDDL" control based on the project selection.

Everything works fine for the first row - I access the ddl controls via DataSource and read/write new items, but I stumbler over the idea to access the control in the second row?!

There are two ways I tried:

1. I can access any rows via the MainDataSource using "my:myFields/my:timesheetEntries/my:item[_row-number_]/my:project", but I see only the selected value of the project DDL, not the actual control. It means that I can't access all items from the project dropdownlist. Can I somehow cast the control via MainDataSource?!
2. If I access the control via DataSource[_name_], how to get access to the control values from the second row then?!

Actually, in InfoPath, we can't programatically access controls -- only the data fields bound to the control.

If you want cascading dropdowns to filter correctly in a repeating table or section, your best bet would be to use a data source for those dropdowns that connects projects and sections. Are your desired values stored in a database some place? Or can you use an xml file as a secondary data connection with your projects and sections?