Hi Steve,
Although I am not a doctor, I may be able to point you to some resources that might help. Check out this article: Flomax Drug Interactions.
Although the article doesn't mention any specific interaction between the effectiveness of flomax and the pain killing medications you've mentioned, it does say that you should alert all your doctors that you're taking anything that may cause drowsiness (which would most likely include morphine, lortab, and soma).
If you still have questions about interactions between the drugs you are taking, be sure to check with your pharmacist.
-Dan