5 Units to 7 Units – C of O

I am looking to purchase a property in upstate NY. It is currently listed as a 5 unit, and the C of O covers the 5 units. I found out today that a father and son are living in the two studios upstairs (shared bathroom), but this isn't included on the C of O, which is good until Jan. 2021. So, my question is...what are the repercussions? How difficult is it to get the C of O revised? How would you proceed? 

In addition to this, there is currently someone living in the garage as well. Would this need to be added to the C of O as well, making it an 8 unit?