How non entry point (random) process running inside Windows Container could write to docker default log output (stdout)?

Question

So, I have one Windows Container with various processes, .NET and Win32 legacy applications.

First scenario

Entry Point calls myConfigurator.exe, who calls first.exe, who creates a pool of second.exe

Second scenario

Entry Point calls myConfigurator.exe, who calls ServiceMonitor.exe, who initialize my IIS ASP.NET Web Application, who creates a pool of second.exe process

Problem

I'm already using log4net appender to send all logs to elasticsearch, and it's all good.

But, I need to send logs to default docker log too, so datacenter operators can see logs the same way they do with standard/compliant containers, using portainer or any other tool.

Question

How random processes running inside Windows Container could write to default log output?

Knowing how it works, maybe I could write a custom appender or something.

Thanks!

JP