Your dream is rich in imagery and themes that may reveal significant aspects of your subconscious. Here are some interpretations of the elements you experienced:

1. Labyrinth House: The recurring labyrinth symbolizes complexity in your life or mind. It could represent feelings of confusion, a search for direction, or navigating through your emotions and experiences. The fact that it has been present since childhood suggests that these themes may have been persistent in your life.
2. Foster House: This setting may indicate feelings of belonging, nurturing, or a desire for connection. The foster house could represent a place of safety and comfort, possibly reflecting your need for acceptance or support in your waking life.
3. New Friend and Exploration: The girl with brown hair and glasses who you connected with represents a part of yourself or a desire for companionship. Trying on dresses suggests self-exploration, identity, and perhaps a desire to express different aspects of yourself.
4. School and Ties: School often symbolizes learning and personal growth. Your friend losing her tie may represent feelings of insecurity or the struggle to fit in. Helping her find it indicates your caring nature and willingness to support others, but it may also highlight your own concerns about maintaining connections.
5. Dinner Party and Lost Items: Losing your coat and bag could symbolize feelings of vulnerability or loss of identity. The search for these items reflects a desire to reclaim what is important to you. The dinner party scene suggests social pressures and expectations.
6. Supermarket and Choices: The transition to a supermarket with children in roles of authority may reflect feelings about responsibility and maturity. The abundance of cheese and chocolates could symbolize temptations or desires in your life, with your struggle over wanting to steal the chocolate representing inner conflicts about desires versus morality.

Overall, this dream seems to reflect themes of identity, belonging, and the complexities of your social environment. It may be beneficial to explore these feelings in your waking life, perhaps by connecting with supportive friends or engaging in activities that help you express your identity. Consider what aspects of your life feel like a labyrinth and how you might navigate them more effectively.