Complex sentence: The cereal has been subsequently manufactured by numerous other suppliers under a generic brand, often in supermarkets' "own brand" range-in the United Kingdom, Tesco, Sainsbury's and Waitrose have all produced their own versions of the cereal.
Split into simpler sentences: The cereal has been subsequently manufactured by numerous other suppliers under a generic brand, often in supermarkets' "own brand" range. In the United Kingdom, Tesco, Sainsbury's and Waitrose have all produced their own versions of the cereal.