Chief selector Shawn Flegler said regular captain Molineux was on track to take part in next month's T20s.
"I can confirm that she is not going to play any of the ODIs against Bangladesh," he said on Wednesday.
"With Soph being out Tahlia is going to captain in the ODIs, which is great for her and great that she scored a brilliant hundred (on Tuesday) and took a couple of wickets.
"She should go into that series with a lot of confidence."
Allrounder McGrath smashed 154 off 137 deliveries for South Australia against Victoria in the Women's National Cricket League season opener.
The first ODI of a three-match series starts in Brisbane next week.
Gardner, also an allrounder, would become the first Indigenous captain of an Australian cricket side if Molineux does not recover to take the reins in the T20 series against New Zealand, which begins in Sydney on October 18.
"Sophie is on track to play some of the T20s. If she does miss out Ash Gardner will captain in the T20s," Flegler said.
"If Ash gets an opportunity I am sure she will do a great job."
Gardner and McGrath are both vice-captains of the side.
McGrath has traditionally been the preferred option, but did not feature in any games during Australia's T20 World Cup success under Molineux.
Gardner received the backing of Cricket Australia CEO Todd Greenberg last month to remain vice-captain after a highly publicised affair.
If Gardner was to captain the team, Flegler said the media scrutiny would not be a problem.
"I think she will be fine with that," he said.
"The captaincy roles have been endorsed by the (CA) board. Soph will be on tour with us anyway, so I can see that leadership group performing really well. I don't see any issues coming up."
Molineux was still named skipper when Australia's white-ball squad was announced on Wednesday, but quick Darcie Brown is sidelined with a back injury that also has her in doubt for the WBBL, while fellow pacer Lucy Hamilton will miss the ODIs with a quad strain.
Brown played recently in India with the Australia A team, but Flegler said she had "a bit of a disc issue with her back that she has been trying to get on top of".
"Unfortunately it hasn't progressed as quickly as we would have liked," he said.
Brown has returned to Australia and had scans.
"We had to shut her down for a few weeks from bowling and running in particular and there will be a reload period after that," Flegler said.
"Worst case (scenario) is 10 weeks, but we hope it improves quicker than that. We are hopeful she gets back for some WBBL."
Flegler said Hamilton had suffered "a mild quad strain at training".
"But we're hopeful she'll recover in time to be fit and firing for the T20 series," he said.
AUSTRALIA'S WHITE-BALL SQUAD
Sophie Molineux (c), Ashleigh Gardner (vc), Tahlia McGrath (vc), Nicola Carey, Kim Garth, Lucy Hamilton, Alana King, Phoebe Litchfield, Beth Mooney, Ellyse Perry, Megan Schutt, Annabel Sutherland, Georgia Voll, Georgia Wareham
