Hi Jo
When they were in Wales, after William F's death, which would have to be between 1864 and 1867 there is a possible marriage:
Q2 1865 Hollis Thomas & X (can't find a wife), Wrexham, mar. V 11b, P 565. Wrexham district spans part of Cheshire too.
I think you may have to hope that someone with more local knowledge sees this, to determine the burial details. She's not on the NBI.
Good luck
Geoff