Hello, I am Keith, one of the experts on Just Answer, and pleased to be able to help you with your question.
Normally employing a contractor would not bring ir35 into play. However, in the scenario you set out, there is little doubt that HMRC would class this person as an employee and thus she should be paid under PAYE arrangements. If you wish to avoid the palaver of operating a PAYE scheme yourself through one of your companies you could always use a payroll bureau to handle her emoluments.
I do hope that I have shown you a way forward in this matter.
In any event you can always ask the HMRC for guidance on ir35 in their assistance area:
Thank you for your support.