If I understand correctly you want to bind the grid to a page group property which is D_test.pxResults(1).pxPages()
For this you have to first define the D_test, D_test.pxResults() and D_test.pxResults().pxPages() in the pages & classes tab and then configure grid to source from property i.e. D_test.pxResults(1).pxPages
I wanted to add some additional info to this as I was struggling with this for a bit. I have a report definition that joins multiple classes, and I too was loading it with a data page. I then wanted to display the resulting data in a repeat grid in a section.
In using the same structure as OP with a data page constructed like:
You would then first configure pages and classes tab of your section rule to be the following:
Then (assuming section is in the same class as your pxResults page), when configuring repeat grid, you can reference properties on the pxResults page with just .propertyname, and properties in the various other pages like .pxpages(test1).propertyname. If your section and pxResults class are different, I assume you would have to reference those properties by D_test.pxResults.propertyname (but I did not test this out)
.propname construct will work only in the context of the primary page i.e. the page context of the section where it is present. The minute you say topLevelPage.page.pagelist, you will lose the section's page context.