Another thought for a quick non permanent fix. I rotate a cold mist and warm mist humidifier depending on weather and how my sinuses are feeling. Hub HATES hates hates the little old vics warm mist humidifer I use every once in a while, becuase it heats up the room so quickly. That might be an option (if other allergies aren't a huge concern. Sometimes when used too much warm mist can affect carpets and stuff.) But it does warm up a room, that I can say for sure!
(ever see doorway fans? They can transfer heat from one room to another. But the door would have to be open and that might not work, unless you babygated her door to allow for the fans (???) )