Coolant woes..

[Buguyed]

So my wife's X5 M54 has been leaking coolant lately from the drivers side front. I replaced the hoses, expansion tank, and automatic transmission thermostat. The leak still occurs. It leaks down to a point overnight and won't leak anymore. I add about a quart of coolant, bleed it, and the car is fine until it has to sit overnight again. Then it leaks down 1 quart and never more than a quart. After it has leaked, the heater doesn't work well even though the temp needle is rock solid in the middle.

I've looked and can't figure where the French toast the coolant is leaking from! Is there anything else that leaks around there or is it probably a ninja hole in the radiator? Any suggestions help!