In this post I will discuss about how to create multiple value look up to external list using InfoPath.
SharePoint 2010 has functionality to create lookup columns to other list/external list and you can built this using UI and/or SPD also.
Very important point is using UI or SPD you can’t able to create multiple value lookup to external list But you can achieve this by customizing your form in infopath.
- So lets start by opening your list form into InfoPath designer.
- Select Multivalue selection control.
- Create Data Connection using Data Connection Wizard.
- Choose SharePoint Library or List.
- Provide your SharePoint Site’s URL
- Select your external List.
- Choose the fields you want to see in the lookup control.
aanuwizard.com 
Thanks very much for this post. This is exactly what I was looking for.
Is it possible to get the graphics updated, it is very hard to read what it is showing.
but great article!
You cannot filter that column after though! Kinda sucks.
I have created a InfoPath form based upon the “Sharepoint Form Library” template and I don’t have the “Multivalue” control, is there another way to do this if the InfoPath form is based upon a non-default template?
What I’m trying to do is populate the InfoPath form with the project details that are listed in the Sharepoint library once someone selects the project #. Each project has a unique #, and I want the form to automatically pull the project details once they select their project #.