New tenancy/guarantor question

Guarantor

Hi there. I have a tenancy where there has been a relationship breakdown. The male partner has moved out for good and the female is staying with her children. We always take out a rent guarantee and legal expenses insurance (RGI) and I am aware that the female tenants earnings would not be sufficient for the insurance cover.
Her mother is willing to act as a guarantor. I wanted to the check the most straight forward process here... my thoughts were to start a new tenancy with the present tenant and her mother as guarantor (do I include the mother on the tenancy or just the guarantor agreement?)I would put the tenant and her mother through referencing to achieve the RGI cover.I would re-insure the deposit and supply prescribed information, deposit certificate, epc, gas safety again as it is a new tenancy.
Does this sound like a good approach?
Many thanks in advance.