How to add repeating section through rules or programmatically?

Question

Hi,

I have a few strings return from a data connection. In the past, I use concat and add the result to a text box. now, I have a repeating section of dropdown, how do I add additional repeating section so that I can assign each string to each of the dropdown? It would be nice if that can be done using rules. If not, programming is fine too.

Thanks in advance. Your help would be greatly appreciated!