A lot of others may not know this...
Of course, one could PIN the element in place, but this only keeps you from inadvertently moving it. It is still possible to delete it.
To prevent this, you can create a separate Workset for your link, make sure the element is in that workset, then pin the element, and leave the workset Open/Editable by a 'Link Manager' user.
Martin Schmid
Product Line Manager
Mechanical Detailing and Electrical Design
Architecture, Engineering, and Construction
Autodesk, Inc.