Macbook Air (mid 2013) daisy chaining two Dell U2715H?

I have a Macbook Air (mid 2013) and two Dell U2715H monitors.

I am able to connect the one monitor to the Macbook via the DisplayPort-MiniDisplayPort cable. This works great!

Now I want to connect the second monitor. This I can do via the DP1.2 (out) port on the first monitor and then attach it to the MiniDisplayPort in the second. Also works... well, not so great. It just mirrors the first screen.

Is there anyway to tell the Mac (Yosemite) that it's actually two monitors? Both the monitors and the Macbook Air seems to support DP1.2 and MST.

I have read various posts here on StackExchange and other sites, that states that this should both be possible and that it is impossible, so I'm a bit in the dark here.

One of the posts mentioned that it was a driver issue, and that it worked OK on Windows 7 and 8.

Are there any software or third party driver that would make it work?