How long should i hold on to them?.. if i drop and they return, i might be a tad upset because they both can put up some pretty decent numbers..
I say drop them both. Neither of them will make an immediate impact since they both have missed trainning camp will be tad outta shape
Hold on to them until you get accurate info on when they'll be back. If you can be patient for 3-4 weeks, then wait. These guys are priceless once in your roster, especially Niedermeyer who can get you practically any stat you need.