I'm going to pickup my mother-in-law in Sao Paulo and help her quarantine in a third country before she can enter the US. In order to be as efficient as possible, I'm trying to avoid spending a night in SP, as we want her to arrive in the US asap, as we have a newborn waiting at home. I'd have about 2.5 hours to make a T3 to T2 international to International connection for us to travel onward to MEX. Will they allow me to make the airside T3-T2 connection on separate tickets if I have no checked baggage?

I'm thinking that it's not worth risking the connection if I have to go through immigration and exiting procedures, as even without luggage, 2.5 hours isn't a lot. So I'd book the AeroMexico flight for the following day and spend the night in SP. Any info or advice on this T2-T3 airside connection would be appreciated.