I've been doing my research on different airline policies for reward travel with an infant in arms and I know those like Cathay are terrible, whereas AA or British are a little better.

What happens if you book a Cathay redemption with Avios or AA miles? For example, if I were to book Cathay trip using AA miles, would I need to pay the AA policy (10% of ticket, I believe) or would I have to cough up the 25% of the ticket that Cathay requires? It seems like a great way to avoid the Cathay fees if it's possible to book tickets using other one world programs that have better infant policies.

Any insights? Thanks in advance.