Probate Law

I am trying to find out where I can find information regarding probate
law in Texas. My grandfather recently passed away and although my
sister and I were included in the will, we were not notified of the
reading of the will. I have had a couple people tell me this is
illegal and another tell me that it is illegal in Oklahoma (where I
live) but was unsure of the law in Texas. I have already requested a
copy of the will from the county court clerk. Thanks in advance for
any information.