Jmo it is impossible that if police thought they knew who had Leah, that they would hang around hoping he would “make a mistake.” We would have seen SWAT team or the UK equivalent. When missing people are thought to be alive, or not known to be deceased, police will not wait, much less months.
I can’t imagine what their theory is, though. If they knew she was okay and wanted to stay hidden, they would issue a brief statement and close the case. As it is, they are subject to scrutiny, complaints, raised eyebrows, etc...the family should proceed however they wish at this point. Maybe even hire a private investigator...I bet they would be able to raise funds to help.
All jmo