I think you should consider moderating your expectations. You will need to accrue a heck of a lot of miles in a short space of time to have the necessary balance for first flights. I would suggest that business might be realistic, while first probably is not. Having 100,000 AA miles and 50,000 UA miles doesn't really help you, since these are in difference programmes/alliances. I'm sure that there is a complicated way of merging these via some hotel or third party sites, but I suspect there will be some devaluation.
Your next problem is going to be finding availability. To my great surprise, there is actually availability from SFO to BOM on connecting flights on BA through LHR for your dates in business class at the moment, however, you should expect to pay the better part of $1,000 per ticket in charges. If you are willing to do this, you should probably book these today on aa.com
LH is going to be nearly impossible in first, since these seats are not released to partners until just before the flight.