they dont relate to each other.
ILiketotravel is correct - if the payer uses his/her own car insurance (so not to buy insurance from the rental car company), in case there is a claim, the payer's insurance rate will go up - then it will be an issue to spread the future rate increase among all the participants in this trip. It is better to just buy the coverage and be done with it. I wouldn't even use the credit card coverage in this case, for the same reason - as credit card does not fully reimburse the claim, not to mention the time and efforts involved when there is a claim. Been there, done that, I can tell you CC coverage works, but not a simple task to file claim, get reimbursement, and finally, there are items that are NOT covered, or not approved.
ILiketotravel is correct - if the payer uses his/her own car insurance (so not to buy insurance from the rental car company), in case there is a claim, the payer's insurance rate will go up - then it will be an issue to spread the future rate increase among all the participants in this trip. It is better to just buy the coverage and be done with it. I wouldn't even use the credit card coverage in this case, for the same reason - as credit card does not fully reimburse the claim, not to mention the time and efforts involved when there is a claim. Been there, done that, I can tell you CC coverage works, but not a simple task to file claim, get reimbursement, and finally, there are items that are NOT covered, or not approved.