Ask for her biometric card, this may be difficult as she is feeing domestic violence but then again if she remembers her NINO you can check her status on CIS (Searchlight), saying all of that a family reunion “leave to enter/remain” would normally carry a no recourse stipulation but I do not know anymore than what you have stated.
This link below should assist, you and your TA team, for future reference.
https://www.nrpfnetwork.org.uk/information-and-resources/rights-and-entitlements/immigration-status-and-entitlements/who-has-no-recourse-to-public-funds
