FLR(O) Complex situation!!

[fatherAbraham]

Hi all,
I recently got my ILR and also registered my son as a BC. I am actually not married to my baby's mother and we live separately. She has been the sole carer for my boy since birth as my wife does not know i have a son elsewhere. Not that i abandoned them, but things nearly got very messy a while ago. I went through the ukba site and found the FLRO is about the only option available to her. she is a student at the moment.
Please, What documents does she need to apply with aside my son's British passport? She lives with a relative, would that count against her as she doesn't have a tenancy agreement? She doesn't pay council tax as she's on student exemption too. she also just started work last month, how long does she need to be in employment for? I will really appreciate your kind advice and opinion on this matter. Many thanks to you all.