Hi bbouma333 -
Thanks for your tips.
Mister E -- Thanks always, as your suggestion I chose Regiojet where it was available
I finally was able to make all my ticket purchases for 3 of us as follows :
1) sept 8: Regiojet :
Vienna, Hbf - Budapest, Kelenföld - sept 8 - 5:27 PM -> 7:58 PM
Cheapest : Low cost (2nd cl.) - € 68.10
Our flight is scheduled to land at Vienna at 2:30 pm ... this will give us adequate buffer to reach Vienna, Hbf
Best -- with regiojet, if required cancellation is easy and at no cost
2) sept 12: Hungarian Railways ( https://www.mavcsoport.hu/en)
Budapest Keleti - Salzburg Hbf
07:40 Budapest-Keleti -> 12:53 Salzburg Hbf 60
Total cost : € 47 with seat reservation for 3 of us.
Caution -- this website is very tricky to use ... timings get messed up based on where you login from.
3) sept 13:
www.cd.cz
Salzburg Hbf to Praha hl.n
16:11 - 22:12
Total cost : € 52.5
This has two train changes in between : Salzburg Hbf (16:11) -> Linz Hbf (17:35) -> České Budějovice (20:09) -> Praha hl.n (22:12)
This looks tricky .. hope it goes through properly
4) sept 18: Regiojet
Prague, MS (09:12) - Vienna, Hbf (13:15)
This time I chose Standard (2nd cl.) -- for €7 more
Total cost : € 68.1
Again ...with regiojet, if required cancellation is easy and at no cost
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Comments .. red flags .. if you see any, please let me know.
As always -- many thanks for your help.