Custom Service Broker with a lot of DLL files

You can create a folder inside the service broker folder where you can keep all your custom files.

Could you please be a little more specific? An example?

Hi @Nintex_yousef  would you kindly provide an example? 

We had to deploy the solution as we have, our attempts with DLLs in subdirectories failed, I had to upload all DLLs to the "ServiceBroker" directory. 
If there is anyone who would be willing to share experiences and details, ideally real ones, not some theories on how to solve this, I would be very happy.

Just make sure the folder you create has full control rights given to the K2 service account. This is always the way I place custom assemblies in my K2 projects and never faced issues. Take a look at the image above.

Hi ​@PavelS ,

One thing that we do at our end is to combine all dll code into one. If you still have source code try to go through it and combine them in once compiled DLL. If those library are just for reference you can place them in folder of your reference in VS and make them embed. this will make the reference DLL compiled inside the main DLL. You can user the below link as your reference. 
 
c# - Embedding DLLs in a compiled executable - Stack Overflow

Hope this will help with the question you have.