SharePoint to Alfresco Migration (individual files)

I was just wondering is there an easier way to do this than just downloading and reuploading to Alfresco. 
This would be for users who have files stored in SharePoint who require them to be opened in Alfresco on occasion. 
Would the best method be the one mentioned above, or would it be more practical to keep the documents in Alfresco. 

I know Open in App has been recently rolled out, could this be a feature of that?
I still haven't found a list of files that are supported by Open in 

I have very little experience with Alfresco but this was recently raised by a user with this concern, so I said I'd ask here before raising a ticket, as I often get better feedback here. 

Thanks in advance, 
Chris