Complex sentence: The duo also made guest appearances on studio albums by other artists such as Sa-Ra Creative Partners and Black Milk, and they sang in these song such as "U", which would be featured on the latter 2007's recording "Popular Demand".
Split into simpler sentences: The duo also made guest appearances on studio albums by other artists such as Sa-Ra Creative Partners and Black Milk. They also sang on songs such as "U", which was featured on the latter 2007's recording "Popular Demand".