Advice appreciated.My sister bought apartment 2006, 320k.Now worth maybe 220k. She has mortgage of 275k and struggling.I am willing to take a half share in the apt at approx 125k and hope for the best in 2019 or so. The apt will be let at 950 per month.I am confused as to how this will work.If she pays 125 off her mortgage,have I any chance of raising mortgage against the same apartment as 150k will still be outstanding.Would bank agree to transfer half of 275k to me.It is on a very good tracker deal.Would they see any advantage in improving their chances of having mortgage repaid?