Group Capability to be Posts Author

We use our WP as an Intranet and I have created a new User Group called “Managers”. As far as I can see I have copied all the Group Capabilities for the “Contributor” to the “Managers” since I basically want them to be equals.

On of the more important things for the Managers is that the Managers are supposed to be able to be Authors of Posts, i.e. basically the same as Contributors. But I can not change the Posts Author to any of the “Managers”, but I can change it to any of the Contributors.

So, does anyone know if I need to do something else or add any other capability to allow me to set the Posts Author to one of the Managers?

Thank you in advance