I just took the mission from Adalon the Silver dragon. I need her blood to give to the yahoo in Umar Hills. Are there more silver dragons or will I get a chance to kill her after I get her eggs back.

Thanks in advance

Are you an evil character ? If not, you shouldn't even consider attacking someone without being provoked. Adalon helps your final stage of escape after you brought back her eggs, but she will do so in her human form. I really don't know if you could get the blood from her when killing her human form. If you give me a day, I can tell you (because I'm almost finished with underdark), but right now I have to go to bed and catch some sleep because I'm fatigued