They are two different families:

From Ancestry BMD indexes

Marriages 1837-1915 Lancashire
Francis W Kinvig & Alice E Royle mar 1st qtr 1914 Toxteth 8b 254

Births to 1915 & from 1916 Lancashire
Alice R Kinvig mother's maiden name Royle 2nd qtr 1914 Toxteth
Francis J Kinvig mmn Royle 1st qtr 1917 Toxteth
Muriel Kinvig mmn Royle 4th qtr 1918 Toxteth
Edna Kinvig mmn Royle 4th qtr 1920 Toxteth
Elizabeth M Kinvig mmn Royle 3rd qtr 1923 Liverpool

Marriages from 1916 Lancashire
John H Kinvig & Nellie Rhall 2nd qtr 1916 West Derby 8b 810

Births from 1916 Lancashire, details already posted
Eleanor Kinvig mmn Rhall 4th qtr 1918 West Derby (mmn transcribed by Ancestry as Bhalla - image is smudged but ends '--all')
John Kinvig mmn Rhall 3rd qtr 1921 West Derby
Mary E Kinvig mmn Rhall 2nd qtr 1932

searched untill end 1955.

In the marriage entry for John H and Nellie on Ancestry, the 'Find spouse' link doesn't work as they have transcribed Kinvig as 'Kinving' on Nellie Rhall's record. I found her given name by searching with Rhall, Lancashire, 8b and 810, which brought up John H Kinvi(n)g. The name is Kinvig in the image of the record.

It is an unusual surname and I wondered if someone had recorded it wrong somewhere along the line, but there are several Rhall marriages recorded in West Derby between 1916 & 1926.