Kansai-Hiroshima Area Pass / Hiroshima->Kyoto directly?

We are travelling to Japan in October and are planning to purchase the "JR Kansai-Hiroshima Area Pass"; we have a question:

In addition to order journeys covered by this pass, we intend to travel directly from Hiroshima to Kyoto on the Shinkansen and, if possible, without changing trains at Shin-Osaka Station.

We have read some information suggesting that this is possible. Could anyone please confirm this and, if so, explain how to go about making this journey without getting off the train? We understand that this will involve an additional fare for the Osaka-Kyoto leg, but it is not clear to us wheter, if feasible, this payment should be made before boarding or upon arrival Kyoto.

We would appreciate this information, and would be grateful if it could be provided in detail (specifying which trains to take and wich to avoid).

Thank you in advance.