Oh Middie, fortunately you have such a large family. I hope the children are doing as well as possible.
Since it was an 'unattended' death, I assume the police were involved and the medical examiner is doing their job. Don't let them quit until you feel comfortable with the answers they come up with.
If the family is not satisfied with the 1st ME, don't hesitate to call in another one even if it involves moving the body. It may cost but you need to know what happened. If they both concur, then you can accept the answer.
Life is not like the tv programs where everyone is giving many days of work to definately solve the case.
If this is too much Mods, let me know. I'm a retired Funeral Director and Forensic Investigator.
Plus, if you are going in the direction of malpractice, all the information (from 2 MEs especially will help your case - if indeed the drs failed). Demand every record from the police, ME and hospital.
No one tries to cover up but sometimes mistakes are made or info is overlooked. We are all human. Since the body has been interned, another ME can still check all the info and perhaps a 2nd ME would see things that the 1st one missed.