Did you build the DLL from Labview yourself? If so, you just add another VI to the list. This VI accepts the Title of a front panel and top,left,right,bottom value of the front panel (VI property WindowBond). I'm not familiar with building DLLs using Labview so I really could not help you on how to build the DLL, but I believe it can be done (multiple VIs as multiple functions in a single DLL).
To get the windows bonds for a vi, you need to use VI server property. Check out the examples under labview directory. There are plenty of them to demostrate how to use this feature. Joe