This just happened to me on my last hatch.  All of the eggs were supposed to come within a day of each other.  Silkies and pheasants.  Of course the plan didn't work and the pheasant eggs came over a week late.  I did a dry incubation so my biggest worry was lockdown of course.  I use a still air incubator and both plugs were out.  When it was time for lockdown, I positioned the pheasant eggs so that they could be turned through the plug holes rather than opening the bator.  I couldn't do anything about the humidity so I just held my breath.  I fashioned a coat hanger to turn and it worked pretty well.  Once the chickens hatched I let the humidity just drop and then I raised it again for the pheasant lock down.  All went well although the pheasant eggs did get rolled a bit by the chicks that hatched.  
Good luck