Webster was officially added to Australia's squad on Thursday with a 14-man group to now assemble in Adelaide on Monday.
Marsh will also remain as part of that group after pulling up sore following Australia's horror loss in the first Test in Perth.
Webster's call up marks his first into a senior Australian squad after he impressed with two unbeaten half-centuries for Australia A this month.
A late bloomer who will turn 31 on Sunday, Webster made an irresistible call for selection in the past year.
Beau Webster has been ultra consistent with the bat in the Sheffield Shield. (Morgan Hancock/AAP PHOTOS)
He was the leading run-scorer in the Sheffield Shield last summer, with 938 at 58.62 for Tasmania.
The right-hander has then backed that up against this summer, with 448 runs at an average of 56 across all first-class cricket this season.
He can also provide an option with the ball, taking 30 wickets last season for Tasmania while able to hit the pitch hard with his medium pace and also bowl spin.
Webster's form has therefore allowed him to move ahead of Aaron Hardie in Australia's list of allrounders.
The situation also highlights the absence of Cameron Green in Australia's Test line up, particularly given the length of India's second innings.
Marsh was asked to bowl 17 overs in Australia's 295-run defeat in Perth, marking his heaviest workload in any Test since 2019.
Australia also had to turn to Marnus Labuschagne for 6.3 overs of spin and pace, the most he has bowled in any home Test since 2021.
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