The hosts, already 3-0 ahead in the series with the urn secured, reached 578 for five at the break after England had toiled for another session at the Sydney Cricket Ground for the reward of one wicket.
It was Mitchell Marsh who departed for 101 on the delivery after he had secured his second century of the series when Tom Curran cleaned bowled him to break the 169-run partnership between the siblings.
Older brother Shaun will resume on 145 not out with Tim Paine unbeaten on 14 as the Australians look to pile up the runs and exhaust the tourists before putting them back in to bat.
The Western Australian duo had earlier joined the Chappell brothers Ian and Greg (1972) and the Waugh twins Mark and Steve (2001) in scoring centuries in the same innings in an Ashes test.
It must have been particularly sweet given Shaun was a controversial selection for the series, his eighth recall to the test line-up being met with disbelief in some quarters, and Mitchell brought in for the third test in Perth.
Mitchell was the second to reach the milestone about an hour into the session with two runs past point and Shaun was in such a hurry to congratulate his little brother that he almost ran him out.
The 26-year-old all-rounder only lasted one more ball but was still beaming from ear to ear as he departed having secured his second test century less than a month after his first at the WACA.
Shaun, 34, had started the day on 98 with Australia 479 for four and took just five balls to secure his sixth test century by crunching Moeen Ali (1-152) through the covers for one of the 17 fours he scored in his 278-ball knock.
England took the third new ball and James Anderson (1-56) got some movement but the best chance of removing Shaun Marsh off an outside edge whistled between captain Joe Root and former captain Alastair Cook in the slips.