Three-body FSIs in D+ ---> K- pi+ pi+

We stress the importance of three-body final state interactions in $D^+ \to K^- \p^+ \p^+$. The basic building block is the $Kπ$ amplitude with parameters determined by a fit to elastic LASS data. Based on a vector weak vertex, we can describe the $Kπ$ phase production experimental in the elastic region.