January/February = winter. If she can't afford to arrive in IST a day or two late due to weather related delays I would book her on the TK non stop flight and make arrangements for an airport transfer in IST on arrival. Or, make sure she connects in hubs that are less likely to be affected by weather related delays.
Weather in VIE and BRU can be miserable in winter.
Add, jet lag, a possible language barrier, etc to the scenario and things could backfire. I'm not sure the 23 hour stopover would be worthwhile.
Last edited by startpacking; Sep 9, 2013 at 1:49 pm
Reason: typo