That was my assumption as well, just wanted clarification.
The problem with this approach is that the software would have to add 3 separate rebuys, and divide the various fields by 3 to get the appropriate amounts for each separate rebuy.
There have been some suggestions in the past to add to the add-on/rebuy dialog a quantity field, so you could, for example, purchase 1 rebuy for player A and 3 rebuys for player B. This could be done as just an additional "Quantity" column on those dialogs with a value defaulting to 1. Another approach would be to have a Quantity field in the "Details" section of those dialogs (where you select the profile, fee, chips, etc). The difference being that with having a Quantity column, you can choose a potentially different quantity of rebuys for each player when you rebuy more than one player at a time, but with a single Quantity field in the Details section, if you rebuy more than one player at a time each player receives the same quantity of rebuys. Simpler, but less flexible, as with most trade-offs like this.
Thoughts?