File storage passthrough possible, windows 7?

I have 2 drives both with differant folders.

Is it possible for me to create a folder for example d:\passthrough and have it act like a merge between a folder on drive 1 and another folder on drive 2.

Read only would be fine, I guess because it would be hard to tell the folder how to act to write operations.

Another scenario would be:

1 folder called g:\myFolder when viewed should list the contents of itself AS WELL AS the contents of another folder. Any copy operations would be delegated to the drive that has the most freespace.

Is any of this possible with Windows 7?

From superuser

• For the first question, Windows 7 Libraries should do it.

  As for the second one... it will be a little trickier, and I don't really know if you could do something like that using Windows 7.

• Number two cannot be done in Windows. Linux and FreeBSD have UnionFS which does this.

  Another alternative is to setup the second drive as a JBOD attached to the first. Now it just shows up as one big drive. This has its limitations though.