Hi lismo, hopefully these can be of some help to you
These are the brackets that were screwed directly onto the metal parcel shelf, the brackets fit over the rear speakers
& these are the mouting hooks for the baby seats, they were screwed onto the centre screwhole on the metal brackets shown above
A picture of my rear shelf. U can't see it in that photo, but where the 6x9 speaker covers are there should be in it's place a circular plastic speaker cover with the anchor points coming out from them, hence why the brackets fit over the speakers
Hope these pics give u an idea of what you need. I had to yank out my back seat just to take the parcel shelf cover off, but there's a tutorial in the D.I.Y section on how to remove the rear seat if you're interested.
Cheers