This will probably come in handy again one day so might as well make a note of it…. how to describe oldest and youngest siblings
Filho primogénito – the oldest son
Irmão do meio – the middle brother
Irmão mais novo – the youngest brother
O benjamim is the youngest but can also mean the favourite son, or the favourite in a group, apparently. Ugh! Why would the youngest be your favourite? The first born is clearly the best. Oh and caçula just means youngest, not favourite.
Luso 