How can I transfer Photos 9 library from Sonoma to an older machine running Catalina?
I've just finally finished scanning all of our family photo albums and merging them with all the family phone pictures and tagging and sorting everything. That monster project was all done on my M1 MacBook Pro running Photos 9 on Sonoma. I'd like to put all that on my wife's computer now, but it's a much older MacBook Pro that can go no further than Catalina and Photos 5. I tried copying my "Photos Library.photoslibrary" package to her machine, but it Photos on her machine won't accept it because the library was built using a newer version of Photos. Is there any way I can export my entire library and it's organizational structure (folders and albums) to her Catalina machine so it will accept it? I get that Sonoma likely has a bunch of features that Catalina doesn't, but I was looking for some kind of lowest common denominator export/import for just the basics (without having to buy a new laptop!).
[Re-Titled by Moderator]
MacBook Pro (M1, 2020)