@Alice595 In my experience, people who are looking for a discount right out of the gate are going to be difficult, inconsiderate guests, and I don't entertain their inquiries. I'm assuming this is just an inquiry, rather than a booking request, since they're trying to haggle with you. If that's the case, you don't need to accept or decline, just send a written response. I would just say something like:
Thanks for your inquiry. We feel that our property is priced fairly for the amenities offered, and we are not able to offer any further discount to our rates.
We wish you the best of luck in finding accommodations, and safe travels to you and your family.
Regards,
Alice
People like this have likely sent the same cookie cutter message to 10 hosts anyways, hoping that someone is desperate enough to bite.