In Florida, my landlord specified on the lease that only me and one roommate can occupy the premises. My roommate did not sign the lease from the landlord. The Sublease signed by me and my roommate also stated that only I and he could occupy the premises. This sublease was provided to the landlord who approved it verbally. My roommate, the subtenant, has become engaged to a French citizen and has sponsored her to immigrate with a K-1 fiancee visa. I nor the landlord are willing to modify the leases to allow a third occupant, but my roommate is insistent that she will be moving in or he will be moving out and ceasing rent payments to me. What should I do when a jobless French immigrant knocks on my door?
Your subtenant's personal issues are not your problem. They knew the rules when they moved in, and are non-negotiable in your particular situation.
Remind your subtenant that they agreed to the terms of the sublease between you, and it does not allow for an additional occupant. Let them know IN NO UNCERTAIN TERMS that if they try to move this person into the property, that you will ALL face eviction for having the additional and unauthorized occupant residing in the rental unit. Then leave it at that.
If the subtenant decides they would rather move out, that's fine too. If you have a signed fixed-term subtenant lease with them, they (the subtenant) will remain liable for the rent due under that lease until a replacement is found, or until the end of that sublease, whichever occurs first. (As their LL, you will have the duty to make reasonable efforts to find yourself a new subtenant as well, and you will remain responsible for the missing share of rent under your own lease with the LL until that happens, whether the subtenant pays or not.)