Tenant wants ex-GF and Unauthorized Roommate out. Can I evict?

[Samer Abbas]

I'm in MI.  My otherwise great tenant contacted me yesterday explaining that he and his girlfriend broke up.  He's been staying elsewhere for a while because he didn't want to kick her small kids out.  Now she has moved in a friend along with two dogs and a cat without my permission.  Pets are not allowed by the lease.  My tenant asked me to evict them and he wants to stay.  The lease is in his name but his girlfriend and her kids were allowed to live there (I included them as "number of people allowed by lease").  The friend who moved in definitely is not allowed to be there.  What can I do?  Do I have the right to evict the girlfriend and friend or is this something the tenant has to do because he allowed it to happen?