Thank you for the replies. I think SSMS used to show a bunch of DIFFs with only the last one checked, but that may have been long ago. Choosing the DIFF I need in mt T-Sql statement worked like a charm. I'll consider creating different files, too, but I fail to see the advantage.
P
Out of curiosity, I just pulled up an older version of SSMS and it does list the differentials separately when they are in a single file.
Part of my reason for separate files is that if something by odd chance happens to one file, I'd rather it affect one backup than numerous backups. And for me, it just seems easier to manage for some things where I would want one backup instead of several.
Sue
I think they added the "timeline" slider in SSMS 2014 or thereabouts.
As for the separate files, another way to look at it is, if you have one big backup file, and one lonely disk sector goes bad under that file, you've lost every backup in that file. If you have multiple files and the same sector goes bad, you only lose one of the files (and as long as it's not the full,) but you can still restore if need be.