so if the system doesnt pay the bookie, where does the credit goes ?
This addon is NOT about the BOOKIE. There are a lot of system accounting things that you just don't need to be concerned with because they don't apply to the addon.
This is all you really need to know.
When Member "A" places a Wager on an Outcome, that amount (called a "Stake") is deducted from their account at that point. That stake value amount is stored as part of the wager record for accounting purposes.
When the Event is settled:
If the Outcome that Member A placed a wager on "Pays Out", the "SYSTEM" (which has UNLIMITED RESERVES for this accounting purpose) will return the Stake amount plus the Winnings to Member A.
If the Outcome that Member A placed a wager on does NOT pay out AND you have the option set to Pay the Bookie any stakes from outcomes that don't pay out, the "SYSTEM" will pay the Bookie all the stakes from that outcome. If you don't have the option set, the bookie gets nothing.
That is it. Nothing more, Nothing less. Sportsbook is not about the Bookie, however, there is a nice feature that does REWARD your bookies by them getting all the stakes when outcomes do not payout. This was added as an incentive to reward Members for Creating Events.
As for Cash systems, I use my own, so I don't have an opinion on any of the others. I've tested [bd] bank several years ago and it worked OK. I do know that Dragon Byte Credits has some built in Sportsbook functionality, what it IS tho, I don't know (you'd need to ask them).