Well, if it's any consolation... any time I knew of a group project and the group refused to mesh and one or two ended up doing it... the prof gave that one or two the grade and the others failed it! We cannot force anyone to do anything... and if the project is designed for a group effort, then there's no way it be a complete project if done by one or two. (Unless there is plenty of time...)

Do your best, that's all you can do. Worrying doesn't help... we know this.