It has been a while since anyone asked how to do it for maps but I had to deal with splitting map YTD myself and feel like this might be helpful for some other people trying to do this.
Here is a nice guide I found and that worked for me - Split YTD Files For Maps or : The nightmare of figuring out how to stream a split map YTD file! - #6 by dark20345
Only thing is that you need to name your YTD files in particular way - test, test_2, test_3…(that is only way it worked for me and I also made a comment on that in reply to the guide)
Hope this is gonna be useful to anyone