m. (1) Ralph S Scott, (2) Harry Powys Greenwood.

This looks very strongly like her birth:

First name(s) Dorothy Annie Bunting
Last name Fraser
Gender Female
Birth year 1891
Birth place Partick, Lanark, Scotland
Father's first name(s) John
Father's last name Fraser
Mother's first name(s) Rose
Mother's last name Frost Fraser
Residence Scotland
Place Partick
County Lanarkshire
Country Scotland
Record set Scotland Births & Baptisms 1564-1950

So she was 34 at marriage to Harry P Greenwood.

Her birth date was on the 1939 Register, as was that of her widowed mother Rose Frost (see the entries in Harry Greenwood’s Notes).
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There were two Scott births on FreeBMD with a mother’s name of Fraser:

Surname First name(s) Mother District Vol Page
Births Mar 1921   (>99%)
Scott Joseph V Fraser Brighton 2b 348
Births Dec 1924   (>99%)
Scott John W Fraser Aylsham 4b 121

Short of spending £20 on birth certificates, my suspicion is that the the biological evidence is that she was highly fertile, from the two births soon after her marriage to Harry Greenwood.  Accordingly I would expect much the same, factoring in the contraceptive facilities of those time, for her marriage with Ralph Scott; but this did not happen and I reckon these two births in 1921 andm 1924 were not from her and Ralph Scott.
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Her death index:

First name(s) DOROTHY ANNIE B
Last name GREENWOOD
Gender Female
Birth day 16
Birth month 11
Birth year 1891
Death quarter 1
Death year 1979
District SALISBURY
County Wiltshire
Volume 23
Page 2432
Country England
Record set England & Wales deaths 1837-2007
_________________

Her probate index:

GREENWOOD, Dorothy Annie Bunting of Woodlands Sandleheath, Fordingbridge Hants died 5 March 1979 Probate Winchester 27 April £16228  793306597D
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Her M.I. index:

First name(s) DOROTHY A B
Last name GREENWOOD
Birth year 1891
Death year 1979
Age 88
Burial year 1979
Burial day 5
Burial month Mar
Place ROCKBOURNE
County Hampshire
Country England
Notes wife of Harry Powys
Reference 45683
Record set Wiltshire Memorial Inscription Index
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Their marriage index:

First name(s) DOROTHY A L
Last name FRASER
Marriage quarter 3
Marriage year 1913
MarriageFinder™ DOROTHY A L FRASER married
RALPH S SCOTT
Spouse's last name SCOTT
District BROMLEY
District number -
County Kent
Country England
Volume 2A
Page 1321
Record set England & Wales marriages 1837-2008
________________

There were two court cases:

(a) Reference: J 77/1876/8622

Description:
Divorce Court File: 8622. Appellant: Dorothy Annie Bunting Scott. Respondent: Ralph Stayner Scott. Type: Wife's petition for restitution of conjugal rights [wrcr].
Date: 1922
Held by: The National Archives, Kew
Legal status: Public Record(s)
Language: English
Closure status: Open Document, Open Description
Context of this record Browse by Reference
All departments
J - Records of the Supreme Court of Judicature and related courts
Records of the Family Division and predecessors
J 77 - Court for Divorce and Matrimonial Causes, later Supreme Court of Judicature: Divorce and Matrimonial Causes Files
1920-1922 Series
J 77/1876 - Divorce and matrimonial cause files, described at item level
J 77/1876/8622 - Divorce Court File: 8622. Appellant: Dorothy Annie Bunting Scott. Respondent: Ralph...

(b) Reference: J 77/2075/4984

Description:
Divorce Court File: 4984. Appellant: Dorothy Annie Bunting Scott. Respondent: Ralph Stayner Scott. Type: Wife's petition for divorce [wd].
Date: 1924
Held by: The National Archives, Kew
Legal status: Public Record(s)
Language: English
Closure status: Open Document, Open Description
Context of this record Browse by Reference
All departments
J - Records of the Supreme Court of Judicature and related courts
Records of the Family Division and predecessors
J 77 - Court for Divorce and Matrimonial Causes, later Supreme Court of Judicature: Divorce and Matrimonial Causes Files
1922-1925 Series
J 77/2075 - Divorce and matrimonial cause files, described at item level
J 77/2075/4984 - Divorce Court File: 4984. Appellant: Dorothy Annie Bunting Scott. Respondent: Ralph...
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Their marriage:

Surname First name(s) Spouse District Vol Page
Marriages Sep 1926   (>99%)
Fraser Dorothy A B Greenwood Paddington 1a 211
Greenwood Harry P Scott Paddington 1a 211 Additional information available - click on Info button
Greenwood Harry P Fraser Paddington 1a 211 Additional information available - click on Info button
Scott Dorothy A B Greenwood Paddington 1a 211

On both the birth certificates for their children is makes it clear that she was born Fraser and seems to have married previously a Scott.