The three youngsters will reportedly be let go by the club this summer when their contracts expire.
None of the three have ever made a first-team appearance for the claret and blues and are now expected to follow left-back Lewis Kinsella and goalkeeper Charlie Bannister out the exit door when their deals expire at the end of next month.
Kinsella and Bannister both confirmed their impending departures on Twitter earlier this week, while it also thought that defender Ben Swift could be let go just 18 months after being signed from non-league side Maidstone United.
Fellow youngsters Tom Leggett and Kodi-Lyons-Foster are reportedly facing uncertain futures at Villa Park as well and could also be cut loose during the end-of-season clear-out.
Siegrist, 24, joined Villa from hometown club FC Basel in 2009 with a reputation as one of Europe’s top goalkeeping prospects but has since seen injuries hamper his progress.
The 6ft 4in stopper, who proved an integral part of Switzerland’s 2009 Under-17 World Cup-winning side, spent the first half of the season on loan at National League outfit Solihull Moors before finishing the campaign with Wycombe Wanderers and could join the Chairboys permanently this summer.
Donacien, 22, also enjoyed a brief stint at Wycombe earlier this term but played the majority of the season with League Two rivals Newport County, making 31 total appearances for the Welsh club from October onwards.
The ex-Tottenham Hotspur academy product, who can play at centre-half or right-back, was named on Villa's first-team bench twice during the 2013-14 season under Paul Lambert, but he has not been involved with the senior squad since.
Webb, meanwhile, has impressed at right-back for the Under-21s over the past two seasons after helping Villa win the NextGen Series in 2013 alongside Donacien and has trained with the first-team on a regular basis.
However, the 20-year-old has never made the matchday squad and has not experienced any senior football out on loan either.