Convert emitted object with the same parent structure

I can set as emitter multiple object with parents using group (emitter > [hair] > Render > group > Whole Group) , but when these object are convert from the emitter they are separate items (lost the child structure)

this is the original object I would duplicate with emitters (items grouped):

but this is the result with the parent structure lost.


Here’s an sample:
grass-sample.blend.zip (387 KB)

Another small issue I notice is that the objects are emitted “flat”; I’ve played a bit the the emission settings but I didn’t find a way to have object rotated according the plane’s face normals. Any way

If… more detail are needed, I’ll try my best to provide them.