Commercial Tenant Interesting Situation

[Marshall Rousseau]

Hi all. I rented out a tiny commercial space to some ladies that wanted to open a retail clothing store. 10 days after move in they had a falling out and one of them moved her portion of the merchandise out of the store the next day. That individual now wants out of the year long lease. The other individual wants to continue leasing the space but wants to change business to a combo craft store and tanning bed salon and is requesting I add a 220 v outlet for a single tanning bed. I told them I would comply with all of this but they would lose their deposit and the tenant who is staying would need to replenish the initial deposit account. I would add the outlet at my own cost. I also told the tenant she would need a new business license and insurance appropriate for the new business model. I do not think this is being done properly and transparency is lacking, but she already has tenant rights. 

To what extent should I be verifying that they have the correct licensing?  What would you do in this situation? I am concerned that this could turn ugly.