Hmmm, I don’t understand what you mean, sorry.

Aren’t we both talking about the same thing?

Normally, updating is like this:

               Internet
            /        |       \
           /          |        \
       SBS    Client1    Client2

What you want is

               Internet
                     |
                     |
                   SBS
               /           \
             /              \
       Client1        Client2

Or not?