In the BBEC SDK for 2.8 and 2.9, when you try and create Data Form Add In specs, most of the UI models are not appearing. This is from the window prompting the user to specify the UI model they want to modify. In the folder being searched (in this instance, C:\InfinityServer\SDK2.8\SDK\DLLReferences) the UI models are present.
Please note, there are client-critical customizations waiting to be created by Servicesthat depend on these options due in mid-March.
Download and install the latest version and patch, if applicable.