My wife and I have 2 Galaxy phones (A71 and A51) and (recently) 2 Galaxy Watch (both Galaxy Watch 4) and all these registered to one Samsung account. A single Google account is also currently used for all 4 devices. Problem is, this seems to cross-reference a few things under the 2 watches (and phones). For example, I did a short cycling workout yesterday and it shows on my watch summary (great!) but was also added to my wife's workout summary (not great!). We would like to keep these things separate. However, to separate workouts and other notifications, I am not sure if it would be sufficient to create a second Samsung account (with only her A51 and Samsung watch in it) or we would also need to create a second Google account as well. In short, we are not sure if the cross-referencing is caused by the single Samsung account or the single Google account (or both). Any advice?
If you and your wife use only Samsung Health, then separating the Samsung accounts will solve the issue. However, if you also use Google Fit ( or any other activity app connected to Google account), then you will need separate Google accounts as well.
Also note, that watch 4 requires a Google account to sign in. So better to create separate Google and Samsung accounts.