John Dempsey (Brooklyn Dempseys) - Mariah's brother

Family tree I created via ancestry site (their tool is better than mine!):

1900 US census, Park Ave, Brooklyn. Is this him? This would be Mariah's brother.

1910 US census, Heyward St, Brooklyn:

The "9|5" column heading means 9 children born, 5 living.

1915 NY census, Heyward St again:

It looks like the surviving children are: Margaret, Edward, Julia, Catherine, and Mary. What happens to them?

 1920 US census.  John emigrated 1883, Mary 1887:

Brooklyn Citizen newspaper, January 8, 1929:

He had more brothers than this, very confusing ...

and the only Thomas Dempsey we've seen is Bernard's brother ... unless ... ? Unless: obits at the time only list LIVING siblings. So, Bernard Dempsey dies 1926 in the UK, and would not get listed. What about other siblings? Already deceased?

1. John's son Edward, 1915 NY census, Franklin Ave, Brooklyn:

1920 US census, Bergen Ave, Brooklyn:

It looks like Edward's son John dies 1927; trying to locate records on that.

1930 US census, Nostrand Ave, Brooklyn:

1940 US census, E 39th St, Brooklyn:

Aunt-in-law? 

Alice's maiden name:

Edward's WW1 draft card (1917):

WW2 draft card:

Contact is Mrs Jerome Thompson ... Edward's daughter, Marie Alice. She marries Jerome 1940.

His draft card:

Edward dies, 1950:

2. Julia (John's daughter) marries Sylvester Perry, 1940 US census, 90th Ave, Queens:

3. Margaret (John's daughter) marries John O'Keefe. 1940 census, 88th Ave, Queens:

Margaret's mother lives with them, since John has died 1929.

Their son John (1917-1986) serves in WW2: