Unless your HR department includes a registered migration agent, I wouldn't take their word for it, and I can say this because I'm an HR Manager :-)
Condition 8502 is the one to look for..."The holder of the visa must not enter Australia before the entry to Australia of a person specified in the visa." If she doesn't have this stated on her grant notice, then this condition does not apply.
186 visa - Temporary Residence Transition stream
Granted Dec 2013