The 1911 census lists at 9b Carfin Road, Wishaw, Parish of Dalziel
Bartho Carroll, head, 48, married, puddler iron trade, born Bothwell
Annie Carroll, wife, 48, married 7 years, 6 children, 4 living, born Cambusnethan
Annie Boreland, daughter, 16, single, shop assistant, born Cambusnethan
Jeanie Boreland, daughter, 12, school, born Bellshill
Mary Carroll, daughter, 5, born Bellshill
Kitty Carroll, daughter, 3, born Bellshill
Bartholomew Carroll married Annie Wilson or Boreland in Glasgow in 1904. At 48, she is unlikely to have had another child after the 1911 census, so it does appear that Nancy can't be Mary's sister unless Annie Boreland was also known as Nancy Carroll, which also seems unlikely.
However there is a death of Annie Watson Wilson or Borland or Carroll, aged 85, in Dalziel in 1953. If this is accurate it would mean she was really only 43 in 1911, and another child is possible.
In 1901 at Borland's Land, Craigneuk, are
Annie Borland, head, widow, 32, grocer, born Wishaw
Annie W Borland, daughter, 7, school, born Wishaw
Jennie M Borland, daughter, 2, born Craigneuk
Joan Borland, under 1 year, born Craigneuk
Elizabeth McIntosh, aunt, widow, 72, born Wishaw
Annie Wilson and John Borland were married in Cambusnethan in 1894.
There is a death in Barrhead in 1998 of an Agnes Carroll, other surname McLaughlin, mother's maiden surname Wilson, aged 84. This implies a birth in 1913/1914, which is just about possible if the younger age for Annie Wilson or Borland or Carroll is correct. However I don't see an obvious marriage, though there are various marriages of Ann Carrol(l)s to McLaughlins and variants, so I may be entirely wrong about her.
(Geography: Most of Motherwell in in the parish of Dalziel. Most of Wishaw is in the parish of Cambusnethan. But Wishaw extends into Dalziel, and Motherwell into Cambusnethan.)
Who was the executor of Mary Carroll's will?