Question about new tenant before end of existing lease

[Kenneth Tuan]

Hello all,

I am currently leasing a condo to 3 tenants. The lease is scheduled to end 7/31/21. Two tenants are renewing the lease and there will be a new tenant moving in as the third occupant. Rent is currently paid through the end of the lease term. The new tenant would like to move in one week before the end of the current lease term. One of the previous tenants has already moved out.

My question:

As the landlord, can I simply let the new tenant move in before the current lease ends, or do I need to have a separate contract or addendum to the new lease to indicate that the new tenant is moving in early? I am planning on having all tenants sign a new lease starting 8/1/21.

What would the risk be (if any) if I did not do anything and simply let the new tenant move in?