I'd wait till the daff foliage completes it's energy cycle before disturbing the area. I'd think the offending interlopers could be eliminated then, weed grasses roots usually don't penetrate to deeply. I'd think the daff bulbs would lie below the grass weed roots allowing their removal while leaving the daffs safe at that point. once the grass was removed, you might want to dig some of the daffs out to ease potential over crowding because if left too crowded their ability to continue to bloom nicely will decrease. Removed daffs could then be used to extend the blooming show area in subsequent springs.
