url rewrite for sub-directories in multisite

Hi,

I have a multisite wp install. What I want is to have a rule that displays the url as a sub-directory of another site (www.example.com/xxx/blog) but fetch the content from my multisite install (blog.xxx.com).
I have two different sites in IIS7 for the same, one that has the blogs install and another with example site. I tried writing the following set of rules to achieve this –
1. Redirection from blog.xxx.com to https://www.example.com/xxx/blog/
2. Rewrite from blog.xxx.com to https://www.example.com/xxx/blog/

I could achieve the first one but then it would again not display the contents(rewrite) from blog.xxx.com
I know I may be doing something wrong, but is there any way I could achieve this?

Please help!! Thanks in advance!!