Bruce Robison and Kelly Willis welcomed their fourth child on Tuesday morning (Jan. 10). They named him Joseph Willis Robison. He weighed 8 pounds, 4 ounces. Their oldest child, Deral Otis, turns 5 this month. Twins Abigail and Benjamin will be 3 in April. Robison's songwriting credits include "Angry All the Time," "Desperately" and "Travelin' Soldier." Willis is one of Austin's most popular country singer-songwriters.