You’re right about Referback.
With ReferBack your commission is calculated on each individual casino. This means that your marketing efforts with client casinos are never affected. For example, if your Casino Revenue for The Gaming Club is in negative at the end of the month, this number is set to zero, and won’t negatively affect your other Casino Revenue amounts generated from the other Belle Rock Entertainment super-group casinos.
Wager Profits and Casino Rewards — I couldn’t find anything about bundling on either website. If a group doesn’t bundle, it seems like they would point this out somewhere — it is a great selling point worth mentioning. I haven’t had a big winner at either of these places, so I don’t know if a negative balance at one casino would affect the other. I’ll take your word on Wager Profits, though, since you’re sure about that one. 
Does anyone know if Casino Rewards bundles?
Fortune Affiliates — I don’t have a copy of the old T&Cs (which apply to me and many of the older affiliates here), so I don’t know if the casinos are bundled or not (for the older affiliates). I don’t promote FA anymore, and I never had a winner during the time I did promote them. The new terms (effective Sep. 1, 2005) don’t specify whether the casinos are bundled or not. Does anyone know the answer to this question? Are the Fortune casinos bundled or not?
I checked on Vegas Partner as well. VP does not bundle. This applies to all affiliates, old and new. :satisfied