WP site in multisite install as a subdirectory of apart site

Hello Everybody.

Could you please help me?
I’m trying a unsusual setup, is it possible?

I have a IIS hosting spacing, in a certaing hosting provider. Primary tech is .net, but php and mysql are enabled too.

In this space I have a website running in, say, c:\siteA (eg: http://www.sitea.com). No wordpress here, just pure Asp.Net/C#, since it is a web app in fact.

I also have a WordPress 4.1 MultiSite in, say, c:\siteB. This multisite is running fine 5 different sites, so I have 5 domain mappings (ex: http://www.first.com, http://www.second.com, etc.) pointing to this IIS app (it is php, but as long as it runs on Windows, it is BEFORE an IIS aplication).

Until now everything was fine. So I decided to create a blog for my C# app. I would like it to be a folder of SiteA, but be handled as just another site in my multisite WordPress). So, http://www.sitea.com/blog should be my 6th site in the same WordPress (not another instalation).

It is possible?

I just cant figure out how to route (or redirect, or such) any requests for /blog to another site. Or any other arrange to achieve the same result.

Any thoughts?

Thanks in advance for your time.