Linux Unity: Recognize dependent dll files

I have been trying to use DllImport ("filename.dll") in C# Unity and found below things

Unity/C# is able to recognize independent .dll files ie If dll A is not dependent on any other dlls it is recognized

Unity/C# is not able to recognize dependent .dll files ie If dll A is not dependent on dll B,dll C,dll D etc then dll A is not recognized, although all the 4 dlls( A,B,C,D dlls ) are in same location

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I have used dependency Walker for UnityInterface2.dll and found out that it depends on OpenNI2.dll, NiTE2.dll, msvcp90d.dll and kernel32.dll. I have placed all of these in project folder of Unity and also in 4.5(.net of mono) folder , but the issue still persists.

Can I know how do I make C# code recognize a dll (UnityInterface2.dll) which depends on other dlls (OpenNI2.dll, NiTE2.dll, msvcp90d.dll and kernel32.dll) in Linux ? Please help