When you delete a feature, in the delete dialogue if you press 'advanced' you choose which child features to keep or delete along with the feature.
If you choose not to delete, the child features (now with no parent) will be highlighted as having an error. For example, a fillet would appear red and you would have to reassign to an edge by editing the feature.
I hope this helps,
you didnt just help, you have completely solved my problem:) I had unchecked setting of deleting dialogue, so pressing delete key didnt show dialogue but it deleted feature and all its children in one step.
Thank you very much