Complex sentence: Bluebirds are often given as they are believed to bless the new house with happiness and good luck, though in modern day it is more customary to provide bluebird-themed paraphernalia such as china.
Split into simpler sentences: Bluebirds are often given as they are believed to bless the new house with happiness and good luck. In modern day it is also customary to provide bluebird-themed paraphernalia such as china.