Yep, there are some models of 7th Gen Corollas like ours that have the folding rear seats, including Sprinters. In order for them to work, you'd need to install the latches for the seats to click into (there are already holes pre-drilled, but they're not threaded so you'd have to use a bolt and nut), you'd also need the metal pivot piece that goes in the middle of the two seats so that they can fold (the holes aren't pre-drilled for that so you sort of have to guess where it goes, which could make the alignment a nightmare), and finally you will need to drill the holes for the brackets on each side of the rear seats nearest the doors (so they can pivot when folded down and to give each side of the seat support). Oh yeah, there's also little clips for the cushion pads on the side of the seats, but the holes for those are already there.
I recently bought a full set of Sprinter GT seats and I was going to convert my fixed rear seats to the folding ones, but decided it wasn't really worth the stress of getting everything aligned properly. It would be a simple conversion if ALL of the holes were pre-drilled, but the fact that you have to guess where the main centre pivot goes (as there is no outline etc) makes it very difficult. If you had the patience, you could always put the seats in place and then trace around the pivot where you think it 'should' go, but there's no saying it'll be perfect.
I may get around to the conversion one day, but it's not really at the top of my list right now. If you do happen to do it then let me know as it may give me some sort of incentive

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Here's some photos I just took of the various parts you'll need to fit the seats once you get them (so be sure to grab these parts off the donor car while you're there) -
Latch (only one shown in the photo, but you'll need two) -
Metal centre pivot (the second photo just demonstrates how it works) -
Bracket on the each side of the seats (closest to the doors) -