Multi line text background in Motion

I'm doing a quick project in Motion and I want to have some text pop up occasionally in a defined area. I want the text to have a background to each line with a gap between lines. I've used the Align and Link behaviours to place a rectangle behind... hoping it would follow by line but this puts a rectangle behind the whole block of text. Is there a simple way to get this to be multiline? Would be grateful of any help.