Any simple way to fold the rear seats back?

[HDS]

I got a 2007 Yaris and we got 18 month old twin boys and they're frankly growing out of the car. It wouldn't be a big deal if the rear seats could fold back a bit, then we'd get more leg room for the kids as the sit in their car seats, but they only fold forward from the factory.

I'm wondering if there's some simple mod to get them to lean back just a little bit? Or am I out of luck here?

Eventually we'll have to get a new and bigger car but I was hoping to put it off for a while yet. It's been a pretty nice car, had it since 2009 and put 165,000km on it.