A grandson, John COOMBS (1785-1869), married Frances Maria BROWNE (1789-1868).
They had nine children:

John COOMBS (1810-       )
Frances Maria COOMBS (1815-1868) married Robert William LYALL
Lydia COOMBS (1816-1900) married James WEDLOCK
Charles Wedmore COOMBS (1818-1902) married Mary Ann SEWARD
Caroline Eliza COOMBS (1820-       )
Susannah COOMBS (1823-1907) married William Holoman STOKES
George COOMBS (1825-1825)
Esther COOMBS (1826-       )
George COOMBS (1831-       )

The second and fourth of these emigrated to New Zealand:

Frances Maria COOMBS emigrated to Tasmania in 1836.   There she met Robert William LYALL who had been transported to Tasmania on the convict ship "Argyle".   He received his pardon and married Frances Maria at Launceston on 28 February 1837.   Their first child, Robert William was born in Melbourne in 1840.   The family moved to New Zealand in the early 1840s and had four children there and adopted another (James).   In New Zealand the family used the name Coombs or Coombes rather than Lyall.   In the 1860s the family moved from Auckland to Dunedin.

Charles Wedmore COOMBS married Mary Ann SEWARD at Reading on 27 April 1844.   Mary Ann was born in 1824, the eldest of six children of Henry Henry SEWARD and Elizabeth (nee BALLARD) who were married at Shinfield, near Reading, in 1823.   Two sons of Charles and Mary Ann were born in Reading and another at Bermondsey where the second son died aged 3 years.  The family emigrated to New Zealand in 1855 and two more sons were born in Auckland, but the youngest died aged 2 years in 1862.   Later that year the family moved to Dunedin.

As with most family names, this family is in the records with various spellings in England in earlier centuries, examples being COMB, COMBE, COMBS, COOMBS and COOMBES.
The family of Charles Wedmore COOMBS uses that spelling.
The spelling is either COOMBES or COOMBS in the family of Frances Maria and Robert William although Robert (jnr), James and John Walter Lyall COOMBES used that spelling only.

Another naming feature in the family is the use of the name Lyall as a second or third given name.   There were at least 80 examples by 2008.   18 of these are shown in the first two generations of family tree of Frances Maria Coombes on this website.