Can my partner adopt your 22 year old daughter?

In most jurisdictions, an adult cannot be legally adopted by a partner or anyone else, as adoption typically applies to minors. However, if the 22-year-old wishes to establish a legal relationship with your partner, they could explore options like guardianship or creating a legal document that formalizes their relationship. It's advisable to consult a legal professional to understand the specific laws and options available in your area.