On Windows and IIS, to use JMS with a sub-directory, you have to go in IIS management and create a virtual disk that correspond to the root directory of your master website (not the sub-directorty).
This will simulate the case of the domain or sub-domain that must be assigned to the same directory than the master.
See tutorial step 10 & 11 that will redirect you to the documentation to configure the hosting server on IIS.
See
/faq#sec-112
So in summary,
Go in IIS management and create a virtual disk (ie. slave1) that is assign to the same directory than your master website.
So after this operation, you should be able to access your website with either
www.domain.com
or
www.domain.com/slave1
The expected result is that you arrive to the front-end of your master website.
This will allow you to check that you have provided the correct directory path when you have defined the virtual disk.
Once you have that, you can go in JMS and define the slave1
Site id = slave1
domain =
www.domain.com/slave1
That's all.
You can do that also with domain or sub-domain that you have to define in IIS in such way that you always assign the same document root directory as the master website.
All the domain, sub-domain or sub-directories must use the same directory path when the Symbolic Link is forbidden.