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