Tenant wants additional dogs to stay with her

[Jennifer Sleider]

My tenant moved here from out of state without her husband. She brought one of her three dogs with her. The lease specifically states that one dog is allowed and gives a clear description of that one dog that is allowed. 

 The husband visits every so often. The last time he came here they asked if they could bring there other two dogs with them. I agreed as long as I had a written email request with very specific dates on when they would arrive and leave. 

When he left, they switched which dog they left at the house. Which is not with accordance to the lease. 

Now she just informed me that her husband would be moving to the state permanently and asked if her husband could bring the two other dogs for the remainder of the lease (end of July). 

I think this is utterly crazy that they would ask this. I NEED some help with how to phrase my response and so that she understands that she violated the lease when she switched the dog. 

Help!!