Make a Obsolete Part Available on a BOM
Find an existing BOM
 
 
Depress the pulldown next to the History and Select BOM History, all parts will be displayed, including the parts that have been obsoleted.
 
 
Highlight the part that has been obsoleted and enter the item detail screen, depress the edit button and remove the obsolete date or change it to a later date.
 
 
Now the part is available to use.