COMMENT FROM A PERSON FOLLOWING THIS THREAD
He reminded me your sportsbook DOES NOT have to offer Open Parlays to play these plays as a 3 team parlay.
He does the following: (Dollar amounts are just examples)
1st bet: He bets $100. If it wins,
2nd bet: He bets the $100 + profits from the 1st bet. If it wins,
3rd bet: He bets the bet amount from the 2nd bet + profits from the 2nd bet.
If the 3rd bet wins - he has completed the 3 team parlay.
Ex)
1st bet amount $100 - it wins - profit $25
2nd bet amount $125 - it wins - profit $40
3rd bet amount $165 - it wins - profit $55
TOTAL 3 Team Parlay Profit - +120.
If any of the bets LOSE, he starts over again with the 1st bet amount of $100.
I hope this information is helpful.