I am not sure if this has been answered before but I had a question related to Mileage Plus membership and earning for an infant.
I am aware of the fact that lap infants do not earn any miles, PQF or PQPs but what about Lifetime Flight Miles that accrue towards the Million Miler status? Can I add the UA MP of an infant at check-in at the airport (unable to do it online) or is it just not possible to earn these Lifetime Flight Miles as well until the child turns 2 and a separate seat is bought?