opening modalwindow from another modalwindow by closing pare

Q. How can we open a new modalwindow from another opened modal window(urlattach approach) ?

You can use the following approach:

var w2 = parent.dhxWins.createWindow(“w2”, x,y, width,height);

where dhxWins is dhtmlxWindow object that was initialized in the parent window

How to close parent  popup window without closing child windows.

If you mean that you want to close dhtmlxwindow and don’t close dhtmlxwindow inside its iframe, it isn’t possible.