I have booked a pair of SEA-DFW-LHR business class award tickets on AA using AS miles.

My final destination is CDG. When I booked the tickets, I thought we might spend the night in London and then Eurostar to Paris the next day. However, plans have changed, and I now want to got to Paris on the same day that we arrive at LHR.

If I purchase a connecting leg on BA from LHR to CDG, will AA/BA be willing to merge the award ticket with the purchased ticket?

Specifically, can I check my luggage all the way to CDG?

If my award AA flight is delayed and I miss my BA connection, will BA be willing to book me on the next flight?

What is the best way to handle this?

Thanks in advance.

J