How to load a registry free COM dll in plugin dll which is loaded by third party application?

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C#3.5

C++11

I have got the registry free COM working with a sample application following the steps given here. https://msdn.microsoft.com/en-us/library/ms973913.aspx[^]

Now I need to load the same reg free COM from a dll and not from an application directly. I tried making a manifest file for a dll, but it can't find the dll.
Is that possible to change the application maniest to assembly manifest of my plugin dll and load reg free COM from there?

I didn't find much information on this scenario.

Thanks.