Complex sentence: After the death of longtime girlfriend L'Wren Scott, Jagger started a relationship with ballerina Melanie Hamrick, which resulted in Deveraux Octavian Basil Jagger, who was born on 8 December 2016.
Split into simpler sentences: After the death of longtime girlfriend L'Wren Scott, Jagger started a relationship with ballerina Melanie Hamrick. Their child, Deveraux Octavian Basil Jagger, was born on 8 December 2016.