Please help? How can I add comments about each photo I scan and import to LR Classic?

See this thread for some insights https://community.adobe.com/t5/lightroom-classic/how-can-i-export-people-tags-with-associated-faces-to-the-web/td-p/9435570

The names LRc assigns in Facial Recognition are exported in the XMP:Subject and IPTC:Keywords fields.

If you are doing this because the pictures will eventually be displayed on a website or other online resource for the family, then it’s worth thinking about the big picture, because that will guide how you do it in Lightroom Classic.

For example, if you will be using a genealogy website that reads the Title, Description/Caption, and Keywords fields of the IPTC standard, then you will definitely want to make sure that you properly fill out those IPTC fields in the Metadata panel in Lightroom Classic. You don’t have to use every field, but you should gain an understanding of which fields will be of value on whatever website or application the images will eventually make them available to the family.

I don’t know a lot about genealogy websites, but it looks like some can use face regions tied to person keywords (tags). If yours does, then it might be important to use the face regions in Lightroom Classic, because then you would be able to tie a person’s name keyword to a specific face in a group photo. When person keywords are used without face regions, it can be hard to figure out who is who in an old group photo.

The main point I am making is that if you are going to add these photos to a geneaology or photo gallery service that can get person information out of photos in a certain standard way, you want to structure your data entry in Lightroom Classic to be consistent with that. Instead of just typing info into a comments or caption field.

I don't use it, but I assume you've already looked at LRc's Facial Recognition feature. I did just see a note that the names only live in LRc and will not be exported to files metadata.

You might like this free Plugin for Lightroom-Classic from John Beardsworth-

Big Note – Lightroom Solutions

Lightroom Classic has no "Notes" section to add info to images but you can effectively add notes by using keywords and/or metadata fields such as 'Title' or 'Caption'. To do this select the picture, open the library module, and go to either the Keyword tool or Metadata tool to fill in the info as needed. You can also add people's names by pressing the face icon at the bottom of the screen, or press 'O'. 

I'm not cretain how names and info you're adding to the images will translate once the images are exported from Lightroom. That is something you may want to look into.