We can import a an IFC file to magnet modeller but the IFC file can not be modified in any way. It would be great to have the ability to do some actual modifications in Site to the IFC or just integrating it to the model for editing. This would open up new customer groups from vertical construction related customers.
We are looking into the functionality that you are referencing. At this point the improvements will not make it in the next version but it is definitely something I want to get done.
When you say modification in Site, can you give me some examples of what you would like to do? Even if the edits were done in Modeler what kind of edits other than creating points for stakeout would you have in mind. Any and all information helps and is welcomed.