Airline loyalty programs have become more popular and attractive in the last few years, with airlines offering customers more and more ways to earn and spend miles. Several carriers worldwide allow family pooling, giving a group of family or friends a chance to share miles.United Airlinesrecently launched MileagePlus miles pooling, becoming the first major US carrier to allow members of its loyalty program to use such a feature. Let's take a look at how this can be achieved.