This is a very common practice, it's like having an umbrella company own many different companies, that makes the profit or loss easier to use to the advantage of the umbrella company, depending on which way the profit or loss needs to go, for instance, if DL show a large profit and had to pay tax then that profit can be shared with poet to reduce the tax burden, this is a very simplistic explanation but you get the just of it, I am sure there are also other reasons for this structure as well.