She and Ms Turner told the BBC that they wanted to “do what’s right by them” by holding an auction, with all the proceeds going towards Naturaleza y Animales.
“It made my parents very happy when they were there,” Ms Turner added.
Asked how she felt about the daughters’ pledge, Ms McNally said she was “brought to tears” when she heard about it.
“It would be such a wonderful thing to do and their parents would be so proud and so happy about that gesture on their behalf,” she added.
Ms O’Loughlin said she and her sister had been speaking to the British Consulate and were planning to fly out to Valencia when it was safe to travel.
A spokesperson for the UK Foreign, Commonwealth and Development Office said staff were supporting the family and that they were in contact with the local authorities.