Be careful. Usually tinkering with houserules, if you overlook something, you can make it up on the spot. If there is real money at stake, suddenly the game becomes much more serious and the ability to quickly tweak something which might be in one player's favor or another is gone.
From your initial idea, I see several dramatic flaws. First is that Risk is ...
The official mahjong rules do not allow for "cross" bets by players on each other, or by outside parties on or against players.
Now this lady may have been playing by "house" rules in "her" games. But those rules do not apply to your table unless you all agree to them.
This question was discussed in this BGG thread.
The only answer I found at all convincing was: in a 3-player game, if your hand is marginal, the big bet may convince your opponents to put their own interests aside and work together to set you. If you make a small bet on a similar hand, your opponents might play less aggressively to defeat you--each trying ...
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Stand on soft 17
No mention of shoe emptying rules
Splitting up to 3 times (total of 4 hands)
Double down after splitting is allowed
Not explicitly mentioned but unlikely due to one card after split Ace
One card each after splitting an ace (and no resplit)
Ace and ten after split is 21
The dealer does check for ...
I have considered & re-considered the concept of involving a gambling aspect to the classic game of Risk. I have come to the conclusion that playing this classic game should not involve money as people whom like money games will gravitate towards poker & people who like strategy & balance of power will gravitate to Risk.
The best games of Risk ...
I would recommend another approach:
Each player can buy treasury bonds for every country. You play with the countries in which you have a majority of bonds. You can still attack your enemy, but when you do that, remember that someday that country you weaken may be yours because you have more treasury bonds that the other players.
But wait! Don't bother ...