During the quest about Angeline’s daughter it might be not possible even to find Aldis. It is possible that he died during attack on Solitude. In that case some easiest way is to bring Aldis to player 🙂
To bring Aldis to your current location you have to issue command:
player.placeatme 0041fb8 from game console
And now we can have a chat with him and proceed with quest. Enjoy!