I am trying to coordinate travel arrangements for my Stepdaughters (wife's daughters aged 15 & 18) who are soon to receive their immigrant visas to USA from Philippines.

Typically, my wife and I fly from Manila to Shanghai on Cebu Pacific Airlines (fully booked in advance) and then fly standby from Shanghai to Chicago on American Airlines. This flight arrangement seems to require a Chinese visa which is properly obtained even though we are never in the Shanghai airport for more than 24 hours and never have a problem getting seats on the standby flight selected. It seems that the "24hour/48hour transit within the airport without a visa" exemption does not work because a standby outgoing flight reservation is not considered a "final destination ticket with booked seats". My wife and I have been denied on the Manila -> Shanghai flight by Cebu Pacific Airlines in the past for a lack of a visa because we believed that the exemption applied to our travel plans. Was this rule incorrectly interpreted and applied to us? If yes, how can I insure that this rule is correctly interpreted and applied to the situation for us and for Stepdaughters?

Assuming that the exemption does not apply, I am trying to understand what visa classification is possible and applicable so that my Stepdaughters can travel along with us to USA for their immigration process.

It seems that a Transit "G" visa is most applicable but the requirement for an "onward air ticket" seems a bit unclear. Does a standby flight reservation satisfy the "onward air ticket" requirement? If satisfactory, what documentation is required to show a valid reservation as such? Also, what other documentation or procedures are required for the approval of this visa type (in person submission only or 3rd party submission allowed, NBI clearance, school ID, Affidavit of Consent to Immigrate/Travel, etc.)?