Can tenants have visitors to stay overnight

Hi I rent out a 2 bed flat to 2 people who work together but are not in any relationship.
Its quite a small flat and one tenant has upset the other by letting his wife and 2 small childeren stay over christmas for 2 weeks. I can understand the other tenants issues as 3 adults and 2 kids in this small space would not be nice. Is there anyting we can do to stop them having visitors or only have them for a few days?
Thanks Amanda

Hi Amanda

If it’s small place then you could say that not more than on visitor at a time for health and safety because of overcrowding and only for a day or two.

As council’s would not like overcrowding.

Where I am renting flats flats are small and if tenants have visitors they find alternative for visitors