Welcome, and I'm hoping some good current suggestions may be forthcoming.
I've had some success with P.S. Bangkok (3345 N Clark St) on getting suggestions or modifications on the regional Thai dishes for gluten-free, vegan, or allergy-suceptible relatives - withholding fish sauce or dried shrimp or crab and working with soy or vegetable or chicken. I think they see a lot of that traffic and can be trusted with a clear explanation.
I'm fairly certain that some of the board Thai favorites (Rainbow, Aroy, Sticky Rice, ATK) also have goodwill to accommodate and that it would just come down to how separate prep areas are (depending on severity of allergy) and how clear the communication can be in a potentially busy dining time. I would think striking for a lull (very late lunch, very early dinner, etc.) for your first experiment might yield best results.
For Chinese, I'd consider the newly refreshed Chengdu Impression (
http://www.chengduimpression.com) or the newer N. Michigan location of Lao Sze Chuan, where you are more likely to find Tony Hu himself, who I've seen have frank, practical conversations with people about allergies (more suggestions of dishes than modifications), and which has a newer kitchen. Good luck!