Hi Jasmine , on the free BMD UK site , Free until your buy a certificate , but easy to search there are three children to Arthur and Margaret Mckenzie registered in Liverpool :

Susan M 1955
Elizabeth R 1957
Sandra J 1959

To 1983 (as far as you can go on the FreeBMD) no sign of the three daughters marrying.

On the free BT white page site there are S and E Mckenzie's in Liverpool , one of the Pay white pages shows a Susan M and Elizabeth R , but no details without paying.

The free BMD site is www.freebmd.org.uk/

Good Luck
David Dwyer