Unfortunately, you cannot import any roster once you start your "myleague" also 2k enforces auto saves which I've been complaining about it for the past two years so you have to start a brand new one. ( if auto save was off , you can restart from a previous point but this doesnt apply to your issue.. sorry this sh!t bothers me from what 2k is doing)
You know you can edit the injuries right? your post doesnt sound like you knew that. go to KD/edit and its the first option once you edit someone ( same menu as where you can change the jersey numbers, birthday, ect) it's conveniently at the bottom. Not that many people know about it . Whats coo is that you can edit the amount of time he's injured ect.. hope this helps.