Delphi: 2 apps sharing the same DLL instance?

[ArgusMike]

Hello,
I am not an experienced programmer. I am looking to solve the following problem:

I have a Delphi application that I will call A.EXE (standard DELPHI Form) that interfaces with a first dll that I will name B.DLL (which I can't modify the source code); basically I am sending data from A.EXE to B.DLL. So I have loaded the B.DLL library in A.EXE

hDLL := LoadLibrary('C:\VBPROJECTS\B.dll');

This part works fine and I can use all the routines in B.DLL to send date from A to B.

Now B.DLL will send me results (validation of the data I sent) from this thru another dll that I will name C.DLL which I have to implement using specific function and procedure names; I am stuck with this.

The problem is I don't know the delay before B.dll calls C.dll, as the service responsible for sending the data may delay up to a few minutes. I want my form (A.EXE) to be notified when B.dll will call C.dll and would like to 'transfer' the data from B to C to A. Is this possible? If I load C.dll as an external library in A.exe, it will not be the same instance that is called by B.dll (which I have no control over). How do I get A.exe and B.dll to use the same C.dll ?? Thanks