Carr Family

My search for this family has been longI finally have some more information. I am hoping someone can help make a connection or provide me with more information
My great Aunt Florence Annie Sayer 1893married her step father in 1918 HarryCarrI knew they had two children as they are mentioned on the death certificates of Florence and Harry but only by initial'sI have finallyfound out the names and also add to the mystery of this family.
Children were
Edwin Wilfred Carr 1920-1981
Ethel M Carr 1921-1993
Diane M Carr-1926-1984
John Carr1922-199
Edith Carr1927-2003
Peter Carr 1924-1996
xxxx CarrI believe is still alive
All born around the Grimsby/Scunthorpe area
I was unable to locate the birth certificatestill this past monthNow here is the mysterythey are registered under a different nameThey are all registeredunder the nameMOOREfather is not recordedmother is listed as Alice MOOREI have the marriage certificates of all those were marriedand they listedthe father has Harry and now are using thesurname Carr
Why are they registered under a differentname , why was the father not recorded as the parents were marriedWhy did Florence record her name as Alice( Florence full name is Florence Annie Sayer, when she married she changed it too Florence ALice Sayer)Is itall too do that in 1918 it was against the law to marry your step father?
Appreciate anyfeed back or connection to this familyThank YOU