Should a Permitted Occupier be a Joint Tenant?

I’ve researched permitted occupiers but still need clarification on the best approach. We have a tenant who has moved from abroad. She mentioned her husband and two children had just arrived in the country. Her husband doesn’t have a job yet, and it’s uncertain if he will. She earns a good salary and has her homeowner brother as a guarantor. She wants her husband to be a permitted occupier.

I’m unsure what to do, as we’ve never had a permitted occupier. Should they complete the application form? Will the guarantor cover them as well? Is it better to have her husband as a joint contract holder instead?