CTC currently has the merge & split feature based on schedule. The split is more or less modeled after TDP split feature (the TDP split is usually convertible to a CTC split). The helper function, on the other hand, is not based on schedule but rather on demand, and both trains would run together, controlled by the first train, as long as needed. Some pieces are implemented, however, the sequence how to get the trains together for the helper function is still open.