Cummins returned home after the second test in Delhi to be with his ailing mother after Australia had dropped 2-0 behind in the four-test series for the Border-Gavaskar Trophy.
Smith led their brilliant turnaround in Indore where they beat India by nine wickets inside three days to secure their place in the final of the World Test Championship (WTC) in June.
Coach Andrew McDonald said Cummins remained in touch with rest of the squad in India.
"He's obviously dealing with what he's dealing with at home but he's still so invested in this group," McDonald told reporters on Saturday.
"Our thoughts are still with him and his family at this difficult time.
"We're in constant contact with him daily, so at the moment he's not here and the test match is a few days away, so we'll discuss with Pat on a daily basis."
Smith led Australia between 2014 and 2018 before he was stripped of the honour following a ball-tampering scandal in South Africa.
He remains Pat Cummins's deputy since the paceman became test captain in November 2021 and has stepped in three times to lead Australia since then.
Smith said he had no ambition to return as a full-time captain at any stage.
"My time is done. It's Pat's team now," Smith told reporters, after inflicting on India what was only their third defeat on home soil in their last 46 tests dating back to 2012.
"I've obviously been able to stand in this week, obviously in tough circumstances with Patty going home. Our thoughts are still with him back home.
"But India is a part of the world I love captaining ... it's probably my favourite place in the world to captain."
Smith marshalled his attack with aplomb, took a stunning catch at leg slip to remove Cheteshwar Pujara at a crucial juncture and overall looked in charge in the frenetic, low-scoring contest.
Former Australia opener Matthew Hayden was among those impressed by Smith's "inspired" captaincy in Indore.
"You could tell that he was right in the match. He has been brilliant. Tactically on point, up for the challenge," Hayden said during commentary.
