Eureka!!
I've now got a copy of the marriage certificate between Charles WILLIAMS & Margaret WILLIAMS which shows that they married on 21 Nov 1870 at Croesor Chapel, Llanfrothen.
The bride, Margaret WILLIAMS is shown as a Spinster, aged 27, living at Bryngelynen, Llanfrothen where her father is shown as William HUGHES (deceased), Farmer.
So I've now got a complete 'line of sight' as follows:-
* Daniel HUGHES, my 2xg gf, bpt 25 May 1801 Beddgelert son of Edward & Catherine HUGHES
* His brother, William HUGHES, bpt 31 May 1807, Beddgelert, son of Edward & Catherine HUGHES
* William's first marriage to Margaret JONES who he married on 22 Jan 1834 at Llanfihangel y traethau
* William & Margaret's third child, Margaret -- with mother as Margaret HUGHES, formerly JONES -- born on 24 Jun 1843 at Bryngelynen, Llanfrothen (the same day as her mother died)
* William's second marriage to Jane OWEN who he married at Parish Church, Llanfrothen on 26 Nov 1846 where William is shown as a Widower with his father as Edward HUGHES
* Margaret's marriage (as above) to Charles WILLIAMS
My sincere thanks to everyone (& in particular, once again to 'EmyrBorth') who helped me come to a very successful conclusion on this aspect of my HUGHES line.
Regards, Rob