Build a Manipulate with Indexed Controls
You can specify the range that you want your controls to cover in Manipulate.
DynamicModule[{n = 5, data = Table[RandomReal[], {20}]}, Column[{Slider[Dynamic[n], {1, 20, 1}], Dynamic[Grid[Table[With[{i = i}, {Slider[Dynamic[data[[i]]]], Dynamic[data[[i]]]}], {i, n}]]]}]]