Comment by afro88

You can put subtasks under stories, and Tim can have his own subtask that represents his contribution. You can also (with an extension) put time against subtasks if leadership/management want to get really pedantic. Each team member should have at least 1 assigned story/task/bug in each sprint, and Tim should have at least x hours logged against subtasks off stories in the sprint.

Or you can, you know, trust your team to deliver the stories they said they could do in a time window, as a whole. Let them figure out the how at the team level.