Marriage Thomas Jones and Mary parry

[llangatwg]

I am looking for a marriage for the above couple approx 1877 in Trecastle Devynock areas Breconshire.  Thomas was a shoemaker.
I can't find a marriage unless Mary has another Christian name.
I know Mary's surname was parry as I made enquiries of Powys registrars of a birth of child and they disclosed her surname to myself.
If I can't find a marriage cert how can I find out who Thomas Jones father was.  Any ideas.
Loads of Thomas Jones Trecastle as you can imagine.
Thanks

[groom]

Don't forget that the name on the child's birth certificate would be the mother's maiden name, so if it was a second marriage she wouldn't have married under that name but under her married name.

[Gadget]

Outside possible ~
Could Mary be a Martha?
There is a possible 3rd q, 1875, Brecknock 11b, 155
Thomas Jones and Martha Parry on same page.

There are 3 possible marriages  on the GRO BMD lists of Thomas Jones to a Mary in the broad time frame but none have Parry as a surname.

Gadget

[llangatwg]

Thanks funnily enough I have made enquiries of Powys registrars for Martha and Thomas.