You have to show financial support. Recently I had a few cases rejected when parents were in a long-term facility, which was financed by the parents' pensions. Since everything was provided by the facility (accommodation, food, care) and the children did not really have to financially support the parents, the DTC transfer was rejected.
But if the children have to make additional financial contributions to pay for the accommodation, then I'd certainly go ahead and claim the DTC amount.
From my experienced, the CRA has made such transfers more and more difficult in the recent years.
