Do you do this on a regular basis ? Are you aware of anything that is published ? Have you ever had it questioned ? I've never been that fortunate. One time did kiosk CI and said no to the weight question but when the TA was tagging them and noticed the weight she charged me $25 ea. Another time flying out of GRR I had two 70# and one 40# and in FC with NW with no charge. For some reason NW cancelled my flight and bumped me to CO coach where I had to pay $130 ($25, $25,$80 for the third). My pleas and Plat status fell on deaf ears. Most airlines warn you to check the baggage restrictions on other airlines when you have multiple airlines on an itinerary.