It would be useful to have an indicator on the Organisation Corporate Structure page which marks which organisation is Primary. It could be marked with a green 'Primary' tick or preferrably a Yes/No column for whether the particular company in the 'tree' is the Primary organisation. The tree by default always shows the Parent organisation at the top regardless of whether the user clicks into the Corporate Structure page via a subsidiary, which is ideal. I think the Primary column is best placed as the second column from the left, after Organisation name.