Valda,
Yes, they are siblings as they all are found in the 1860 Census in Massachusetts living with their mother. There is an older sister named Elizabeth who was born about 1842-43 in England. She came here and settled in Lawrence, Massachusetts and married a man who was also born in England by the name of Joseph Webster. Their son was named Joseph Eli Webster.
As far as noting on the birth certificate to a person's mortality or not. I have not seen the situation happen before and do not believe it would be noted. If I recall, the way that Massachusetts handled sending copies of birth records for genealogical purposes is to send a handwritten copy of the record showing only the vital information. Parents names, address and occupation. Child's name along with the date of birth and place of birth. I am not even sure (I will have to look again) if the parent's country of origin was even noted.
As for searching for Eli's burial. Yes, I have attempted to do so and I have contacted the Vital Statistics offices that cover the majority of records for Massachusetts. But, because I don't have the exact date or town where he died it hasn't been easy. But to answer your question, yes I have searched both for the death record and the burial records.
An interesting fact about some of the larger cities here in the States. My wife sent to New York City on three separate occasions for a birth record that she had previously verified the date and burough. She received "Record Not Found" notices each time and finally another registrar got the order and found the record. So depending on who takes the time to 'look' for the record at the Vital Records offices can determine if it is found or not. Some registrars are more dedicated than others.
When Massachusetts does not have a record at their State Archives, they refer you to the town in which the event happened. At this point, I cannot do that since I don't know what town or city Eli came to or possibly died in. I just recently found that Mary Ann Flathers probably died in Lawrence, Massachusetts, but I have about a ten year span of when this event occured. I also do not know if she died a Flathers or a Robinson. I have to contact them in writing to see what they might be able to find for me.
gflats