My mother owns her own home worth 600k her current mortgage is 45k she's on a disability pension and I live with her and I'm on a carers pension for her this is mental associated we want to loan against the home to build out the back (large block) and then rent the old house out would get roughly 350p/w I'm an only child inherit everything and my mother also has an inheritance of around 250-300k in nz in a home how can we both go on the loan together?