Double eval does seem the right way to go. Been trying it though and have run into some issues; from this post http://www.infopathdev.com/forums/t/14658.aspx?PageIndex=1 I realize I need to do 2 things;
1. Add a default formula for the text box
2. Create a rule on the muliple-item list box
Both of thes with the same double eval formula of course. I've successfully done this, but I think there's a problem with my rule. When I select the desired boxes from the muliple-item box it only populates the last selected item. When I deselect then the items are selected properly, this leads me to believe the issue is with the rule but the formula for the default value of the text box is working properly.
The xpath from my rule gives me
xdMath:Eval(xdMath:Eval(xdXDocument:GetDOM("Suppliers")/dfs:myFields/dfs:dataFields/dfs:Suppliers/@ID[../@Company = current()], 'concat(.,"#;")'), "..")
I'm displaying a filtered ID for an item in the text box.
Any suggestions?
Thanks.