There are a few ways to do this, but the reentrant approach will not work, since all instances of reentrant VIs share the same Front Panel. Here are the possibilities:
(1) Create multiple copies of your GUI VI at edit time, and call them statically or dynamically.
(2) Copy new instances of your GUI VI at run time using the File Copy function and then invoke the GUI VI dynamically
(3) Change your GUI VI's file extension to .VIT so that it is a VI Template. Then open a VI server reference to it multiple times to get multiple instances of the VI and invoke dynamically, as in #2.
Regards,
-Jim