Hi cduc
You haven't mentioned any ages/birthplaces (always a good idea) but is this your couple?
1901 Dorchester (St Peter) Dorset
RG13/2002 folio 36 page 22
36 Cornwall Road (Royal Terrace)
James Hallett, head, 40, fishmonger's manager (worker), Lyme Regis Dorset
Margaret L do., wife, 39, Bournemouth Hants
Jessie K. do., daur, 16, Bournemouth Hants
Carrie L. do., daur, 14, Bournemouth Hants
Margaret L. do., daur, 12, Bournemouth Hants
Elsie S. do., daur, 6, Dorchester Dorset
Caroline Harris, m in law, wid, 74, Alderholt Dorset
Was Margaret a widow when she married James?
* her mother's surname isn't Seek
* there's a noticeable age gap between Margaret & Elsie (also birthplaces are different)