Hi Having read the postings so far would like to add the following. From descriptions diode switching may be possible if both locks share the same supply and readers are dc controlled.4 diodes could be used as follows. Remove 'open' wire from lock release and fit diode in series at both locks .(test to see if working if not reverse diodes.) Feed smoke relay from supply ,switched contact is now connected through a further diode to each controller 'open' contact.
I agree with others on the group this is not the total solution HSE requirements for fire doors are that they must be fail release in fire and must have break-glass release points at each door if no mechanical opener is fitted. As for visual impairment or indeed other disabilities,regulations are in place for correct equipment to suit most needs .IME most disabled people can find a fire exit and open it with ease if the correct equipment is used and visually impaired systems emit a tone when activated or even talk. As already suggested look at the door release before the electronics .
HTH CJ