At the initial release of 3ds Max 2014, you cannot properly use the texture blending utility for displacements in WW. Unfortunately, I have no control over this issue.
Please read more about this problem here (http://area.autodesk.com/forum/t77971). Please leave a post in that thread to encourage the developers to look at the problem. Also, please submit a bug report about this problem with the 3ds Max defect submission form (http://usa.autodesk.com/adsk/servlet/item?id=12331406&siteID=123112&SelProduct=3dsMax). The more people that report this problem, the more likely it will be fixed soon.
I have a fix for this. I will release the fix for this problem this week.