I'm retrofitting dormers onto an existing frame. If my math is correct one of the purlins won't support the load of a shed dormer. Question: Can I tie two purlins together to share the load?

[img]http://www.flickr.com/photos/95237704@N04/8681315100/in/photostream/lightbox/[/img]

The image above shows the dormer profile in red. The pink struts illustrate what I'm proposing. [img:center][/img]