Other North & South America Frequent Flyer Programs - Reward Flight with TAM for Dec

Hi everyone. I wonder if someone could give me some advise.
I'm a *A member and looking to redeem miles on a flight LHR-LIS-GRU-GRU-EZE. Now, the issue I have is that TAM intra S.America open 3 months ahead, but I need to secure my TAP flight as I'm with BMI and they are leaving *A- drama I know. To add to this, TAM is likely to leave *A and join Oneworld with LAN. Do you know what I should do with the 2nd leg I need to book 3 months ahead. Will TAM still be excepting redemption from *A, do TAP have the obligation to help get me to my final destination.
I'm a little stuck!
Thanks for any help

I think the important thing is how Diamond Club see things. Whether TAP or TAM will do something is irrelevant, as your ticket is from BD and they'll ticket it.
TAM leaving * will not happen in the near future, if at all, it's just speculation. (I personally would rather they go to OW, as I will be able to use Avios for short haul flights)
Your best bet is to try to search for seats not leg by leg, but combined, that way the short haul flight may be available with combination with the long haul. It will help if both flights are with TAM, so you can try LHR-GRU-EZE on TAM only.
Otherwise, just take the risk that you might not be able to change the flight and will have to buy the final leg.

My suggestion for you is to issue our LHR-LIS-GRU ticket and purchase your GRU-EZE ticket. If you purchase this ticket today you'll get a better price. ;)

OR, you can issue the LHR-LIS-GRU now and wait for TAM open the GRU-LHR and try to chance your ticket to EZE.

Looking for BMI to leave *A is better to issue your ticket an soon as possible.

I'm in the same situation - trip is LHR - LIS - BSB - EZE overland GIG - FRA - LHR in Feb/March. Don't see there's much else that can be done in my case other than book (which I did at the weekend) LHR - LIS - BSB and GIG - FRA - LHR through Diamond Club and worry about getting from BSB to EZE later. I'm assuming I'll have to buy a ticket but if I can use Avios all the better....