Merging Metadata From Another Photo

I’d like to be able to merge metadata to a photo in my collection from metadata downloaded from my SmugMug site using an app called Smudo. Currently, they don’t support external XMP metadata files for JPEGs, but may be able to this capability. So currently, the metadata is stored in the photo file. The merge I’d like to do is for photo title and cation that I author for the photo on the SmugMug site, and merge them with the same photo in my C1P collection. Does anyone know if this is possible to do either with or without an XMP sidecar file? Thanks! G262