Imessages Screen Sharing

HELP?!
my whole family has macs, and I can use iMessage to screen share with both my sisters, and both of them can screen share with Mom.

Sisters and I have most upto date macOS, mom is on High Sierra (on purpose)

However if I attempt to screen share with mom, both the “Share Screen” and "Ask to share: is gray on BOTH ends. anyone have any idea why?

If you can’t share a screen

In the Messages app on your Mac, if the Share button is dimmed, try the following:

  • Make sure the person youʼre trying to share with is signed in to iCloud using the same Apple ID they used to sign in to Messages.
  • If they can’t sign in to iCloud and Messages using the same Apple ID, open your Contacts app , and make sure your contact card for the person includes both Apple IDs—the one they use to sign in to iCloud, and the one they use in Messages. Then try sharing again. (See Create and manage contacts.)

Tip: You can also share screens without using the Messages app, using macOS screen sharing. See Turn Mac screen sharing on or off.

via Share your screen using Messages on Mac - Apple Support

see also: https://discussions.apple.com/thread/251088037?sortBy=rank

to my knowledge, neither iCloud nor AppleID is required… connection is made via phone # or email address. I have dozens of other contacts in Messages where this feature works just find and non of us are using iCloud

Okay.

Abbie… my apologies… you are correct. After some more research between my sister at Mom’s end, and me at this end, we figured out a few things.

  1. My end is fine, signed into AppleID and iCloud, although I do not recall actually doing either.
  2. On her end, she is signed into AppleID, but the iCloud connection has to be re-established each time a connection is required…

So two question remain

  1. How to make the iCloud sign-in “stick” [note this is on High Sierra]
  2. once that is done, she can ASK to share screen, but I still cannot ask her