Probate from which state

My parents were killed in a rollover accident in which my sister was driving. They were residing in Texas, but were in the process of moving to Idaho. When they reached Idaho, that is when the accident occured. My sister has obtained all my parents important paperwork (due to the fact it was in the vehicle involved in the accident) and she is hording everything she has. We have asked her for that paperwork, and she has refused to turn anything over to us. I will be petitioning the court for the start of probate and to be named executor. After 6 months of waiting for my sister to cooperate, I am no longer willing to wait. 4 out of 5 of the siblings live in the state of Idaho, so we will be filing for probate there, and hope they will accept it from there. No one else lives in Texas anymore, but they do have a home up for sale in Texas. Will there be any problem filing from Idaho. Also my parents were retired, living off Social Security only, home was paid for. Will they need something done with the IRS? I don't believe they needed to file anymore.