Have just done so more reseach
@Tara2 on Mandrills in other Australian Zoos and discovered there is a family group of six at the Adelaide Zoo, including two offspring born 2010 and 2011. The dominant male is named Tabah and was born at Melbourne Zoo 05/04/2005. Given that Melbourne Zoo have a tradition of naming their Mandrills with names starting with the first letter of their mother's name (Louise - Leroy etc.), I'd say it's highly likely that Tabah is the son of Louise's daughter, Timbiri.
There was/is two Mandrills in a zoo in Tasmania, the female was named Lara and I was initially following the theory that she was a relative of Louise. However, as evidenced by their 2010 and 2011 births and Louise - Timbiri, Adelaide Zoo clearly don't follow this naming convention so if Louise was indeed born at Adelaide, it doesn't necessarily mean her and Lara are related.
I've heard about the issue of hybridisation between Mandrills and Drills and your question inspired me to find out more as I previosuly knew little about the situation.
For those who don't know, The Genus
Mandrillus includes two species:
Mandrillus leucophaeus (Drills) and
Mandrillus sphinx (Mandrills). Mandrills and Drills were previously classified under the Genus
Papio (Baboons). I assumed interbreeding between Mandrills and Drills was due to them having a similar appearance (like with Bornean and Sumatran orangutans) but having looked at pictures online of Drills, I really can't understand how they got confused as the same species, considering how colourful the Mandrill is.
And yes
@Astrobird, I also wish Melbourne Zoo had bred more Mandrills when they had the chance. Louise and Timbiri are now post reproductive so new females will need to be imported if they wish to continue breeding Mandrills. I hope more zoos in the region decide to focus on this species, as the world's most colourful mammal, and the largest Old World monkey, they truly are fascinating.