InfoPath Dev

I have a troubling issue.

Scenario:

Parent List: Holds all data for project

Child List: Each Parent Project (data connected) contains multiple action tasks, each with start and stop times. Each listed as a separate item 

I have build a calculated column for my child list in SharePoint 2010 showing the difference in two dates displayed as hours:minutes =IF(Stop<>"",TEXT(Stop-Start,"hh:mm"),"-").

Issue: I want to show a sum of my calculate column in my parent list for specific items linked to the child

 Thank you in advance for anyones help!

So, the parent list is a list? Or a form library?

Just trying to understand if you are using a SharePoint List form in InfoPath?

I'm wondering - I can't recall if calculated columns are available with a standard list connection in InfoPath. If you are using SharePoint 2010, though, I bet the OData service would return your calc'd column...

The Parent List is a custom list created in SharePoint 2010.

Yes, I am using a SharePoint List form in InfoPath

 I am not familiar with OData service, nor do I see that option listed on my data connection wizard.

OData is a REST web service - so you could add a REST connection to the SharePoint OData service. You can find out if you have OData enabled in 2010 using a URL like this:

http://YourSharePointServer/_vti_bin/listdata.svc

With the placeholder text YourSharePointServer replaced with.... your actual SharePoint server.

Something like this would get you your tasks list:

http://YourSharePointServer/_vti_bin/listdata.svc/Tasks

Again, I'm not 100% on whether this will return your calculated column, but my guess is it would.

EDIT: My URL samples went a bit wacky on post, trying again.