Hello Alison

I'm sorry to throw a spanner in the works! Let me know how you get on with the information. The Edwards and Llewelyn families are obviously related.
Your Grandfather was Lewis Llewelyn Rees, born 1891 (December quarter)
GRO Pontypridd volume 11a page 573
I believe that his Mother was Mary Ann Llewelyn and his was father Jenkin Rees (as above). If you look for Jenkin Rees, born Llanddewi Brefi, in 1871, his father also Jenkin Rees is a blacksmith!
Location: Cwmtwrch, Alltygraig, Llanguicke Parish, Glamorgan
Jenkin Rees Head age 56 BLACKSMITH born Llngybi, Cardiganshire
Mary Rees Wife age 42 born Llanddewi, Cardiganshire
John Rees Son age 22 Collier born Llanddewi, Cardiganshire
David Rees Son age 15 Collier born Llanddewi, Cardiganshire
Evan Rees Son age 13 Collier born Llanddewi, Cardiganshire
Margaret Rees Dau age 11 born Llanddewi, Cardiganshire
JENKIN REES Son age 10 Scholar born Llanddewi, Cardiganshire
Herbert Rees Son age 8 Scholar born Llanddewi, Cardiganshire
Rodrick Rees Son age 7 Scholar born Llanguicke
Walter Rees Son age 8 months born Llanguicke
RG10 Piece 5435 Folio 53 Page 6
Of course, you my want to follow this up with purchase of your Grandfather's birth certificate, and the marriage certificate of Mary Ann and Jenkin.

Kindest Regards
Morgan