To answer your first very logical question, why using 4 buses instead of 1, there is actually at least one case where you would really need so.
What case is that?
Well consider the case where you publish a product and you want some technicians to insert four temp sensors which are named S1, S2, S3, S4 each one of which transfers data from a different yet specific apparatus. So, in this case you would have to know if the sensor attached in S1 transfers temp data from apparatus 1 and not 2.
If you use onewire, you would have to ask, via an interface, the technician, during the installation of your product, if the sensor he has attached in order to read temp from apparatus 1 is S1 or S2 or …
Considering the fact that technicians (at least in my country) have a lot in their minds you wouldn’t want to rely on his ability to declare in a software that he has just attached S1 and not S3…
With this in mind I would prefer to have separate passengers on each bus thus having 4 instead of 1 bus.
About the code.
It was a mod on the original code that comes with onewire lib installation. I am not posting due to the unfortunate fact that I accidentally delete it but in simple words, my problem was that all my sensors were reading the same exact value as temp.
Any how I will review the link you have sent and see if it fits my case. Thanx.