How do I open a new document at application startup without opening a new instance of the application?

I have a situation partially covered by other answers in SO, but I cannot find a complete answer. In short, we are trying to use a URL for our specific datatypes that, when double clicked, open our app and load those datasets into that app. We have this part of the job.

(for example, the url might look like this: resource: //shaders/basic_shader.hlsl)

What we would like to do is prevent new instances of the application from opening when we double click on a new URL. For example, let's say we have a URL that opens a shader in our shader editor. When you click that resource url, it will open our shader editor. When the new shader url is clicked, we would like to open the shader in the current application launch and open the new shader in a new tab in our editor.

We can easily detect if another instance of our application is running. A problem we don't know how to easily fix is ​​to tell the current application launch to open this new file for editing. This behavior is very similar to Apple Finder.

On unix, you can mimic this behavior by opening some named pipe and then new applications could check if that pipe is active and then send the document data down the pipe. Is there a more standard Windows way to achieve this behavior?

We need a C / C ++ solution. Thank.