Attached Link: http://www.daz3d.com/support/tutorial/index.php?id=46

*The Tailor is NOT able to change a V2 dress into a V3 dress.*

Yes, it can. Though you need a "mannikin" to do it. There's a V3-V2 one, and a M3-M2 one, at the DAZ site. (In the Tutorial Arcana section.)

The Tailor doesn't work all the time, but it's useful often enough that I'm glad I have it.