Hello! @Alex Ng
Sorry it's taken a while for me to reply, but I have an idea of what you can do I find it easier to solve these problems by playing with the data itself so forgive me if it doesn't work exactly right
I don't use pickers very much, but I think they add the column that is in the picker? So, I would create the column 'Project Detail' or 'Project Scopes' (whatever you'd like to call it) in the data set you are using, and only fill it in next to the "Application Design, Dev, & Support" ones that you want to give the scopes to. This could be done in another mapping table and looked up in the table you are reporting from.
E.g.
Project Parent | Project Name | Project Scope
Application Design, Dev, & Support | Billable IT Project | Division Wide
Might be best to use the project code but wasn't sure if that was available.
Then, when you click on Project Detail/Scope, it should add that column and show the scope for each line, and be blank for any that aren't in the App Design bit. If you'd like to call out that they don't have a scope, add 'No Project Scope' to everything else that isn't in App Design.
I think you can then add the Project Detail/Scope column to the grouped section so that it appears in the 'Service' column along with the other bits of detail (as I think that's where you'd want it) but I have had issues with adding picker columns to that sort of thing before.
If I've completely missed the mark, you've already done it, or I'm just really confusing, please do say! I'll try to come back and explain more if needed, but hopefully this will help if you haven't already managed to get it done.