The term says
Originally Posted by t&c
3.2 Qantas will use best efforts to advise Members of material changes to these Terms and Conditions and, where such changes will limit Benefits:
(a) where the Benefit is provided by Qantas, to give Members at least 6 months' notice;
(b) where the Benefit is provided by a third party, where possible give Members at least 30 days' notice.
The provision of miles for BA flights would seem to be a benefit provided by BA and so would be 30 days where possible