Manhattan routing is what you get when you connect pins that are multiples of 90 degrees for most interconnects. Avoid cobra_p2p(), bend_strt_bend_p2p(), vipers and mambas. There are ways to restrict sbend() or sbend_p2p() angles to 45 degrees with the Amax keyword.
To understand your question better, would you have a picture on what you would like to achieve or expect and what you get?
Maybe you refer to routing groups of waveguides?