Yep been there done that. Can confirm everything said above is spot on.
To add to the point above: sharing direct links usually fails because of how Amazon handles session security. Honestly it is probably safer to just do...
To add to the point above: unfortunately native syncing is broken. I had issues with items disappearing in Household. Use share Amazon Cart Extension ...
Are you all using the same regional Amazon domain? Syncing issues often arise from regional mismatches between users. For maximum reliability, ensure ...