There are various records which appear to relate to David Flynn the 20 year old son who is listed as a shoe maker in the 1861 census:
In the Birmingham Trade Directory 1868, David Flynn is listed as a boot maker at 21 Branston Street
In the 1871 Census, David Flynn is living at 92 Branston Street. He was 30 years old, born in Ireland, a bootmaker and living with his wife Selina (aged 28) born in Birmingham. The couple had three children: Edward 5, Daniel 4 and James 2.
In the Trade Directory of 1881, David Flynn, bootmaker, is listed at 95 Branston Street.
In the 1881 Census David Flynn, bootmaker, is living at 53 Northwood Street. He is now 40 years old, born in Galway. His wife Selina Flynn is aged 36, a tray polisher born in Warwickshire. But no were children listed.
I also have a baptismal record from St Chad's for a Daniel Jacob Flynn, baptised on 26th February 1869, son of David Flynn and Selina Flynn (nee.Warrant), God parents were Daniel Flynn & Helena Flynn.
All five of these references stand a very strong possibility of being connected to the David Flynn in the family in the 1861 census. David is the right age, he lives in the right area and he's a bootmaker.
What's interesting about this then is that both David and Michael married women named Selina. If the baptism reference is for the same child, Daniel, named in the 1871 census above, it would make him aged 2 at time of baptism.
I have found 4 Census records between 1871 and 1911 (excluding 1891 for no want of searching) which appear to appertain to the oldest brother listed in the Flynn family in the 1861 census, Patrick Flynn:
Living at Cheapside, Deritend, Aston in 1871 were:
Patrick Flynn aged 30 born in Ireland
Bridget aged 28 born in Ireland
Mary Ann aged 5 born in Birmingham
Helen aged 4
David aged 1
Selina aged 0
No occupations given in this Census record
Living at No 5 Court, Cheapside, Aston in 1881 were:
Patrick Flynn aged 42, born Galway, Stamper (Artz)
Bridget Flynn (wife) aged 39 born Ireland (Polisher - Artz)
Mary A Flynn (daughter) aged 15 born in Ireland (Ruler)
Selina Flynn aged 14 born in England (pipe mounter (tobacco)
David Flynn aged 11 scholar
Ellen Flynn aged 10 scholar
Rose Flynn aged 6
John U Flynn aged 4
Edward Flynn aged 3
The same family is recorded in the 1901 census:
Patrick Flynn, 64 year old brass stamper, born in Ireland.
Bridget his wife, aged 56, born in Ireland.
Nellie aged 30, an India rubber saleswoman (daughter).
David aged 28, brass worker.
Rose aged 25 (at home).
Joseph aged 24, a wire maker
Edward aged 22, a gun barrel forger
Arthur aged 15, a tin plate worker.
All of the children were born in Birmingham.
The same family are recorded in the 1911 Census, though at this stage the oldest son David is recorded as the head of the family. It is noticeable that there are 4 single adult sons living in this home plus a widowed sister and a total absence of children:
Address: 14 Hollier Street, Deritend
David Flynn, Head, Single, M, aged 39, born 1872, Clerk Brass Foundry, born Birmingham
Patrick Flynn, Father, Married, M, aged 74, born 1837, Retired, b. Ireland
Bridget, Mother, Married, 48 years, F, aged 70, born 1841, Retired, b.Ireland
Joseph, Brother, Single, M, aged 33, born 1878, Wire Mattress Work, b. Birmingham
Edward, Brother, Single, M, aged 30, born 1881, Brass Burnisher, b. Birmingham
Arthur, Brother, Single, M, aged 34, born 1877, Tin Plate Worker, b.Birmingham
Mary Ann Brome, Sister, Widow, F, aged 44, b.1867, House Keeper, b.Birmingham