Excessive solar gains

My project has very large South East facing windows and the morning sun is causing major solar gains.

I know the architect intends to install blinds - how can I force DDB to see these to prevent the gain?

I have set up the windows with blinds. How do I know the system is taking these into consideration.

Also does it make any difference to the gain calc if I tick the operable box for the windows?

Regards

Craig