I answered a similar question here:- [link text][1] With specific regard to this question you could aproach it from a different approach if you can visit the site you could try indoor mapping the rooms you do know a lot about like the main sales floors for customers, the fitting rooms escalaters, stairs, lifts and corridors etc. and place these inside the shell of the building outline. This can give a very useful mall map and shows were things are still to be found out by someone else later. Try looking or asking staff about evacuation routes and any emergancy maps about to check as these can relate outside doors to inside shops. Using bing's bird view for a clear slanted view of building sidewalls and entrancesis helpful in getting the geometry right when stareing at rooftops in the editors. You can definatly add nodes for sub-features into a larger defined area without a problem the problems begin for some system when you duplicate a feature as both an area and line or a node becuse it can be shown as two seperate things instead of one on the render {there are speacial tagging treatments for highways that are defined as areas too}. putting nodes around the edge of an area rather than close to were the feature actually is is very wrong (if its actually just a door [entrance tagged] that really is on the outside wall then maybe, but not just shop tags that should float in the middle of the known shop. [1]: https://help.openstreetmap.org/questions/24814/mapping-shops-in-a-retail-building-with-more-than-one-entrance?page=1&focusedAnswerId=46725#46725

I answered a similar question here:- [link text][1] With specific regard to this question you could aproach it from a different approach if you can visit the site you could try indoor mapping the rooms you do know a lot about like the main sales floors for customers, the fitting rooms escalaters, stairs, lifts and corridors etc. and place these inside the shell of the building outline. This can give a very useful mall map and shows were things are still to be found out by someone else later. Try looking or asking staff about evacuation routes and any emergancy maps about to check as these can relate outside doors to inside shops. Using bing's bird view for a clear slanted view of building sidewalls and entrancesis helpful in getting the geometry right when stareing at rooftops in the editors. You can definatly add nodes for sub-features into a larger defined area without a problem the problems begin for some system when you duplicate a feature as both an area and line or a node becuse it can be shown as two seperate things instead of one on the render {there are speacial tagging treatments for highways that are defined as areas too}. putting nodes around the edge of an area rather than close to were the feature actually is is very wrong (if its actually just a door [entrance tagged] that really is on the outside wall then maybe, but just shop tags that should float in the middle of the known shop. [1]: https://help.openstreetmap.org/questions/24814/mapping-shops-in-a-retail-building-with-more-than-one-entrance?page=1&focusedAnswerId=46725#46725