During sieges, I want to help but it says your Union has been seiged and I can't get in to use scrolls..

Once your Union is sieges you can no longer play in the war. Sounds to me like union members are not signing up for the war. I was in a union once where noone explained anything. It was frustrating to say the least. My advice is to round the members up in chat and ask about the war. If you can't go to local chat and talk about wanting to join a more active union. Someone would be happy to add you, I'm sure. Also, scrolls are bought with diamonds before the wars even start that is why you're not able to use once the war starts. You're union leader should know all of this in order to have a successful union. Wish I could explain it all, but I'd be here for hours. Good Luck!