Additional tenant move in without notifying me

Landlord Discussion Legal
1

I’m a landlord in Scotland and I am letting out a house with 1 tenant deciding to bring his wife to stay with them without letting us know. The flat was originally rented to him and his brother and it was never mentioned the intention. I only found out after I went for a repair to the house. It seems she has been leaving with them since Dec’24. It’s still okay in terms of overcrowding however, can I create a new tenancy agreement with the new tenant added to the contract and a revised monthly rent? Do I still have to give 3 months notice or as this is a new tenancy agreement can I just start it from the beginning of next month?

Thanks

2

Why would the addition of the tenants wife give cause to alter the monthly rent? Surely you are charging rent for the property as a whole, not on a ‘per tenant’ basis?

I personally would be a bit annoyed that the tenant moved someone else in without mentioning it to me, but I don’t see how that gives the right to change the rent amount unless you’re a hmo?