I am currently working with the nopCommerce source code and trying my best to avoid editing the source at all, but instead using partial classes and plugins that are separat
You can't do that. What partial
basically does is tell the C# compiler to join the two bits of code together.
A bit of a hacky solution is to finish off the class, and then inherit from that and override the methods you want, e.g. here's a simple example:
public partial class A
{
public virtual void X() { }
}
public partial class A
{
public void Y() { }
}
public class B : A
{
public override void X() { }
}