Complex sentence: Erik Sviatchenko is also the son of Ukrainian-born multi artist Sergei Sviatchenko, whom together with Eriks older brother, Philip Sviatchenko, are authors on a fashion inspiring blog, which shows the modern classicist style.
Split into simpler sentences: Erik Sviatchenko is also the son of Ukrainian-born multi artist Sergei Sviatchenko. Together with the elder brother Philip Sviatchenko they hold a fashion inspiring blog which shows the modern classicist style.