I have an upcoming flight booked through an OTA on 957 (TAM) ticket stock.

The itinerary is AMS - LHR(BA) - GRU(BA) - LIM(JJ).

Looking at the punctuality of the AMS - LHR flights, I figure there is a greater than 50% chance I will miss the tight connection at LHR, so I'm considering what re-booking options may be available.

Would BA only consider options to get me to GRU, then expect TAM to accommodate me from there, or would they consider other options to LIM, such as IB via MAD?

How would I go about claiming EU261 in this situation? Would it even be applicable?

I'll be flying Y as a BA Silver.