At a (hopefully) temporary impasse with Margaret GRIFFITHS, nee ROBERTS, but have made what I hope is some progress with her husband, James GRIFFITHS. I am hoping someone can either point me to some other leads, or help me figure out if this all "holds together". It feels fairly solid, at least at the moment:

86185
Entry Number 102
Year 1758
Month Sep
Day 17
Parents Surname GRIFFITH
Child Forenames James
Fathers Forenames Valy[?] (Birth records for Dad list his name as Valentine)
Mothers Forenames Elizabet[h]
Mothers Surname
Residence
Occupation
Officiating Minister
Event Baptism
Memoranda son of
Notes Date could be the 17th
Register Reference P57 IN 1/1
Page Number 15
Parish Chapel Bream

61529
Entry Number 151
Year 1783
Month Nov
Day 1
Grooms Surname GRIFFITHS
Grooms Forenames James
Grooms Age
Groom Condition
Grooms Occupation
Grooms Residence Newland
Grooms Fathers Surname
Grooms Fathers Forenames
Grooms Fathers Occupation
Brides Surname ROBERTS
Brides Forenames Margaret
Brides Age
Brides Condition
Brides Occupation
Brides Residence Newland
Brides Fathers Surname
Brides Fathers Forenames
Brides Fathers Occupation
Licence or Banns Banns
Date of Banns
Signature or Mark Both mark
Witness 1 R Williams
Witness 2 Mark of James Robins
Other Witnesses
Officiating Minister P Ball vicar
Event Marriage
Memoranda
Notes
Register Reference P227 IN 1/8
Page Number 569
Parish Chapel Newland

His parents’ marriage:
Record ID 29218
Entry Number
Year 1754
Month May
Day 9
Grooms Surname GRIFFITHS
Grooms Forenames Valentine
Grooms Age
Groom Condition
Grooms Occupation Collier
Grooms Residence Newland
Grooms Fathers Surname
Grooms Fathers Forenames
Grooms Fathers Occupation
Brides Surname POWEL
Brides Forenames Elizabeth
Brides Age
Brides Condition Spinster
Brides Occupation
Brides Residence of this Parish
Brides Fathers Surname
Brides Fathers Forenames
Brides Fathers Occupation
Licence or Banns Banns

His father’s birth
Record ID 290141
Entry Number
Year 1725
Month Feb
Day 17
Parents Surname GRIFFITH
Child Forenames Valentine
Fathers Forenames George
Mothers Forenames Elizabeth
Mothers Surname
Residence
Occupation
Officiating Minister Tho[mas] Gwillim Vicar
Event Baptism
Memoranda Valentine ye son & Hannah ye daughter
Notes Old style date 1724/25. Brother & sister in same entry. Part of record illegible in BTs
Register Reference P209 IN 1/1
Page Number 48
Parish Chapel Lydney

His mother’s birth:
Record ID 324065
Entry Number
Year 1724
Month Feb
Day 1
Parents Surname POWELL
Child Forenames Eliz
Fathers Forenames William
Mothers Forenames Eliz
Mothers Surname
Residence Lane End
Occupation
Officiating Minister
Event Baptism
Memoranda
Notes Compiled from Latin PRs and BTs Old style date 1723/24
Register Reference P227 IN 1/2
Page Number 142
Parish Chapel Newland

His paternal grandparents’ marriage:
Record ID 75349
Entry Number
Year 1715
Month Aug
Day 24
Grooms Surname GRIFFITH
Grooms Forenames George
Grooms Age
Groom Condition
Grooms Occupation
Grooms Residence Yorkley
Grooms Fathers Surname
Grooms Fathers Forenames
Grooms Fathers Occupation
Brides Surname ELLY
Brides Forenames Eliz
Brides Age
Brides Condition
Brides Occupation
Brides Residence Yorkley
Brides Fathers Surname
Brides Fathers Forenames
Brides Fathers Occupation
Licence or Banns
Date of Banns
Signature or Mark
Witness 1
Witness 2
Other Witnesses
Officiating Minister
Event Marriage
Memoranda
Notes Compiled from Latin PRs and BTs
Register Reference P227 IN 1/2
Page Number 125
Parish Chapel Newland

Paternal grandfather’s birth:
Record ID 322004
Entry Number
Year 1684
Month Oct
Day 13
Parents Surname GRIFFITHS
Child Forenames George
Fathers Forenames John
Mothers Forenames Eliz
Mothers Surname
Residence Yorkley
Occupation
Officiating Minister
Event Baptism
Memoranda
Notes Compiled from Latin PRs and BTs
Register Reference P227 IN 1/2
Page Number 52
Parish Chapel Newland

Paternal grandmother: Elizabeth Elly
His paternal great grandparents’ marriage: John Griffiths and Elizabeth Unknown, before 1684
That’s as far as I was able to go with any certainty on the Griffith’s side

His maternal grandparents’ marriage:
Record ID 75377
Entry Number
Year 1718
Month Apr
Day 21
Grooms Surname POWELL
Grooms Forenames William
Grooms Age
Groom Condition
Grooms Occupation
Grooms Residence Clowerwall
Grooms Fathers Surname
Grooms Fathers Forenames
Grooms Fathers Occupation
Brides Surname MORGAN
Brides Forenames Eliz
Brides Age
Brides Condition
Brides Occupation
Brides Residence Clowerwall
Brides Fathers Surname
Brides Fathers Forenames
Brides Fathers Occupation
Licence or Banns

His maternal grandfather's birth:

322086
Entry Number
Year 1686
Month Jun
Day 7
Parents Surname POWELL
Child Forenames William
Fathers Forenames Walter
Mothers Forenames Ann
Mothers Surname
Residence Clowerwall
Occupation
Officiating Minister
Event Baptism
Memoranda
Notes Compiled from Latin PRs and BTs
Register Reference P227 IN 1/2
Page Number 58
Parish Chapel Newland

His maternal great grandparent’s: Walter Powell and Ann (???)