Is there any way to add new column to an NetTiers model without using codesmith?

it should still fix some issue When I used NetTiers, I was very happy with it to an extent. You really need to learn the best ways to use it. There were definitely some weird bugs, things that had arbitrary limits and so forth. You have to be careful with it but it can definitely improve your productivity if you learn. I know CodeSmith has started putting more resoucres in it. The version 2.3 might be very solid. Although, the latest current stable version may be pretty solid, I haven't used it in awhile.
Honestly, at this point I prefer LLBLGen. I did try SubSonic a couple times. I didn't run into major bugs but I ended up switching, in both cases, to NetTiers. With SubSonic I felt that I was just typing out way too many string literals and it just didn't feel as mature as other alternatives.

I wish this help you I guess you could use NHibernate + MindScape's NHibernate Designer for Visual Studio is free for small models And Nhibernate is open source, BTW: Is NetTiers Dead ?

I think the issue was by ths following , Comfort level is a big one, if you are the primary developer, and you like Entity Framework then that is a very big reason to stick with it. However, in your case, it sounds like you are coming in to a new environment that is using netTiers, you prefer EF, and you want an excuse to switch to your favorite framework.
I have used both frameworks, and I started using both of them about the same time. In my opinion they both have areas they shine in.