McLachlan is one of the few stars that isn’t returning for the final goodbye to Ramsay Street.
Nearly 50 former cast members will be reprising their roles on Thursday evening.
Hollywood star Guy Pearce is returning as Mike Young, a role he left back in 1989. Margot Robbie will also make an appearance as Donna Freedman, though it has not been confirmed if this will be in person or virtually.
Holly Valance, aka Flick Scully, filmed a cameo in London with Natalie Imbruglia (Beth Brennan) for the finale. And speaking of actors-turned-singers, Natalie Bassingthwaighte is returning as Izzy Hoyland.
Jason Donovan is coming back to reprise his role as Charlene’s beau Scott. Delta Goodrem, Jesse Spencer, Kym Valentine and Carla Bonner are also set to return.
Dan McPherson announced on Instagram earlier this year that his character will be back.
“Joel Samuels is back for the final episodes of Neighbours. I couldn't let the show end without saying goodbye," Dan wrote.
The very last episode of Neighbours will air tonight at 7.30 both on 10 and 10 Peach.
For viewers across the pond, Channel 5 has confirmed they will air the finale on Friday, July 29.
WATCH BELOW: Neighbours star Carla Bonner dances