Spam deleted and the people infracted who deserved it. If you find his theory riduculous then say as why it is ridiculous. If you provoke him well then you asked to be insulting. If you then insult him back then you're the same as him.
Saying that Madara's dad is in the coffin has as much probability as Obito being in that coffin. You don't provide any arguments as why it could be his dad.
Saying that Madara's dad is head of the clan is something without any kind of proof as then you're assuming that the position is given from father to soon, something which has never been shown nor indicated. It's not because Itachi's father was the head of the clan that therefore he or Sasuke would become the head of the clan. For the same money it's decided by majority vote, just like the hokage.
You also say that Izuna and Madara must have heard from the MS somewhere, that's not true either, they don't need to have heard it from somewhere. People invent or obtain techniques all the time. Madara and Izuna were both Uchiha prodegies. As Kakashi obtained his MS just like that (relatively seen then) if both of them became so good it's possible it just came spontaneous. That killing your best friend thing has loopholes as both Izuna as Madara obtained MS and as far as I know they were the best of friends, or at least closest to each other. Even though the manga is contradictory with the amount of MS users in history, according to Itachi there was only one and that was Madara. So even taking into account that Izuna had it, it's still very possible they were the first ones so how could their father know it?
And in the case they did hear it from somewhere else I place my money on the Uchiha tablet which has lots of information about the Sharingan written on it.
Saying that it's his did is nothing more than a wild guess at this point.