How To Import Own Created Locomotive And Cabs In Train Sim 4?

Hello I am a 3D artist and learning game development. I created Indian 3D locomotive and Cab.

How can I upload to game using PC Editor in train sim 4 and also how to upload other assets too to make own addon?

There is no process available. I want step by step process to import my assets to unreal and create a proper Blueprint. So that I can make an Indian add on based on that.

Really appreciate if officials or anyone would help me out.