think I have found her in 1841 with her grandparents Joseph Tilly and Nancy at Windmill end RRegis.
So it fits ....They have a son William b 1802
William Tilley - Male Birth: 05 DEC 1802 Rowley Regis, Stafford
other kids include a Richard b 1799
RICHARD TILLEY Christening: 15 MAY 1799 Rowley Regis, Stafford,
Father: JOSEPH TILLEY Mother: ANN
Extracted
William Tilley dies in 1838
1838
TILLEY William Rowley Regis Sandwell Register Office RR/1/209
So then in 1839 Ann Tilley ( married name- maiden name unknown) marries a James Parkes -
James is probably the brother of Ann Parkes -Ann Parkes who married William Baker.
That is how Selina got to know Richard Baker via his auntie Ann Tilley.
So they were step cousins?
I think that fits.....