Buying a tax declaration property with seller just an administrator

We need an advice. We're trying to buy a property with 2 separate tax declaration. The seller is just an administrator and the owner is already dead. She is selling her property and the property beside it. We haven't seen both deed of sale but we saw the tax declarations through a copy from the register of deeds. She doesn't have the copies of the deed of sale etc as it is in her vault in the Philippines and she is abroad. She said if we won't pay down payment, she won't go home. The question is will I risk to pay the downpayment even if I haven't seen the documents? If so, is it legal for an administrator to sell property? And can she transfer the tax declaration name in my name as the owner in the future? Please help