@catlady While the wordings on the sections do not seem to line I up, I can assure you from current personal experience that the bid does in fact follow the team and not the individual athlete. We have made the very switch in question within the the last week. An athlete was previously showing a balance of $469 ($569 minus the $100 downpayment). They have since been switched to the Paid bid team and now show a 0 balance without making any further payments.
Once the bid is registered the profile is created for the team on the Varsity Portal. This is where the parents will go to pay. So the team in essence has been registered for a travel package and each athlete on that package is given a credit (as is worded in the second section). The package is created and then the changes can be made as needed so that "each athlete in the Summit travel package" is accounted and paid for. So as long as the substitutions do not exceed the allowed 25% of original team then the team is still covered in full including the newly added athletes.