Sorry if my question is way to newbie, but I couldn’t find the answer:

We are a family of 4 (two adult and two kids 4 and 8) and want to travel to Orlando from Buenos Aires around October.

I got 70.000km in LAN, 55000BA and 23000AA miles, I know I can get a reward from LAN and BA and purchase the remaining miles from AA.

The question is:

Where to start? As I have to buy 1 ticket should I buy the ticket with AA first and them go to LAN and BA? or should I start with LAN and BA first?, how I can make sure there are seats available?

Again sorry if its too newbie but never got a reward in my life, let along the possibility to get almost 3.

Thanks a lot for the help