Your problem nay be in creating a group for a single item. Don't confuse the limits of a specific controller with the number of pixels allowed on a model because there is no link. Make it a single model with 200 pixels and set the effects for that model to make it do what you want. When you define the output for the show, then you can split the nodes for that tree across 2 or more controllers and let XLights deal with where the data goes to at that point.