I'm working on a DOS app that makes extensive use of Int 21h services 714xh (find first file, find next file, close find). However, I've run into a problem with it over a LAN running winNT. My solution is to use a PB/dll executable with those function as API calls. The API calls will be in the executable instead of a DLL.
The question is, if more than one instance of the DOS app is running and making calls to the PB executable, will there be an instance of the PB executable for each instance of the DOS app or will winNT load in a complete copy of the PB executable?

The way the DOS and windows apps will interface is:

WINAPP creates file interface
DOSAPP writes to file interface
WINAPP checks file interface for info and acts on it if found.
DOSAPP ends by writing close info to file interface
WINAPP closes