Hi Anthony,
We don’t have that functionality in the application at the moment, but you could do it as a customization (it’s probably not a huge deal to do so...you would need to add an Action button on the Original Document Lookup screen when creating the new receiving document to create a new Miscellaneous Receipt instead of being forced to select an existing one from the drop down list and then modify the associated Receiving Lines UI for entry of the new lines).  Reach out to the Services team and they will be able to assist you with this effort.
Thanks,
Reid