Bantam hen with standard rooster?
I keep bantam and standard together a lot. I would jsut advise against hatching any of the eggs. I tried this once, and the chicks all got too big for the little bantam eggs, and had to have complicated assisted hatches. There were only two of them. One died after a few hours, and the other is a very rotten rooster
But as long as you don't plan to hatch her eggs, I'd say it'll be fine. Just watch her a bit closer. She may need a saddle to help her out :-)
*KK means Kraienkoppe