Actually the rules MAY be changed once the convention is in session. There will be a rules committee made up of 112 delegates...two from each state and territory. They will make recommendations to the convention.
The recommendations will be voted on by the delegates. If the combination of Mr. Trump and Mr. Cruz delegates decide they can change the rules. Otherwise they will not be changed.
Please don’t tell me the rules are changed like dirty socks...it’s just not true. No one is trying to subvert the voter.
Let me see, when did the current rules come into being? Last presidential election I believe. And now they are being changed again. Seems that now they change them every election doesn’t it?