Rally Software

I am using this rally API to get the list of all the stories:

https://rally1.rallydev.com/slm/webservice/v2.0/hierarchicalrequirement?query=(Project.Name="My_Parent_Project")&order=OrderString

My_Parent_Project actually do not have any user stories, but its children projects (my_child_1 and my_child_2) has user stories.

Is there any specific field, which I can mention to get all the user stories including child projects.

I can see Rally UI has option to get the data from Child project. So I believe there must be an option to get this data using above API. (They use projectScopeUp=false&setScopedDown=true which doesn't seems to be working with
"hierarchicalrequirement" API.

Hi 

as you are using the query Project.Name=ParentProject, you will only get any user story, that is connected to that specific project. If you want to get all userstories also from the child stories, you will need to set the project instead like this:

<<https://rally1.rallydev.com/slm/webservice/v2.0/hierarchicalrequirement?workspace=https://rally1.rallydev.com/slm/webservice/v2.0/workspace/12345678&project=https://rally1.rallydev.com/slm/webservice/v2.0/project/234567892&fetch=true&start=1&pagesize=20 >>

workspace/12345678  the numbers you will need to change to the workspace OID

project.23456789 again numbers will need to be changed to your parentproject OID

To find the OID, have a look at Find the ObjectID (OID) of Projects, Workspaces, Timeboxes 

Let me know if that helps