My tenant signed a 1 yr lease in May 2018, and now wants to add her?
A lease renewal is, by definition, a new lease agreement. Unless you intend to keep them on month-to-month, you need a new agreement signed anyway. I would also want to background check the husband, just as I would any new tenant, to make sure he qualifies for the lease. If you intended to keep them on month-to-month, then you still need the background check, but you can get by with a lease modification agreement. If you havent done any of these things before, get advice from a real estate agent who deals in rentals, or contact your landlord/tenant attorney, and have them walk you through it. Take notes, so you can (maybe) do the next one on your own.