My wife and I have two different ID numbers for her on our accounts in FS. When I tried to merge her ID number from her account it would not let me. Her number has more Family History work completed and I want to engage it on my account.
For Privacy reasons each living person must be entered manually in each users tree. You cannot merge an id number of a living person you entered in FamilySearch with another id someone else entered. Once you enter the living individuals and link them to their deceased ancestors you will see the same ancestral lines as your wife sees. Below is an article from the FamilySearch Help Center that discusses this. Click on the link and it will take you to the article.
How does Family Tree protect the privacy of living people?
Hope the article suggested in the last posting fully answered your question.
This issue often generates questions and these may have been answered previously. Before posting a question, it may be helpful to you to check if this topic has been addressed previously - You can add keywords (in this case 'ID numbers' or 'living people' ) to the search bar, and other similarly themed questions will appear and may provide you with a quicker answer.