Depending on the situation, we will attach to our own buildings but not others. If the building is one of ours, we can usually modify and/or repair the building or move it from one site to another. Whether or not we can do that for other brands depends on the specifics of that building. It helps to see pictures of the building to do an initial assessment. It is generally not feasible to increase the height of an existing building. In our experience, you are better off selling the building on a venue such as Facebook Marketplace and starting over to get exactly what works for your current needs.