https://www.dotnetzone.gr:443/cs/blogs/abekiaris/archive/2009/11/03/dynamic-type-merging.aspxI hope you all vote on DeveExrpess Issue that will allow us to validate runtime extended existent types. But even if you did not there is an alternative way that my friend Emilio shared with us. I want to add runtime members for my existent Customer classelCommunityServer 2.1 SP3 (Build: 20423.1)