We try and use the Last Name at Birth (LNAB) for each profile as it was used at the time of birth. We try to look for sources that indicate what the last name was at the time of birth. If we have a good source, great, go with that.
Sometimes it is just a guess but, after a discussion, an agreement is made on what to use.
If it is demonstrated that a child used a different LNAB, then we use that alternate spelling for that profile. Often we find that they used several different spellings over time. A discussion is encouraged to determine what to use for the LNAB, we then include the alternate spellings in the Other Last Names field.
Part of the reason for this is Genealogical, but part of it is for WikiTree functionality. We do want to have all the surnames used, listed in the Other Last Names field because this helps with searches for Duplicate profiles.
Once a LNAB is determined. We want to merge all WikiTree duplicates into that WikiTree ID. The reason for this is that the old profiles using alternate WikiTree ID's still exist even though they have been merged. Instead of disappearing, they just get redirected to the chosen WikiTree ID. So if Smith-3 was Merged into Smyth-10, then anywhere Smith-3 was used, a click on that ID will send you to Smyth-10. Smith-3 still exists, it just gets redirected to Smyth-10.
If we catch it early, then all duplicates just get redirected to the Chosen WikiTree ID (LNAB). But when mistakes are made and multiple merged profiles get redirected to a final WikiTree ID, then the computer servers have to route through all the links.
So in this case, we may have Bowton being pointed to Boughton being pointed to Bouton being pointed to Boughton being pointed to a new Bouton. That is a lot of work for the Servers when there are multiple (thousands) of merged profiles throughout WikiTree. Ideally, if caught early, Bowton would be pointed to Bouton. Boughton would be pointed to Bouton and we would not have had to create another Bouton to repoint Boughton back to the new Bouton.
This is why we encourage good sources and open discussion to get everyone in agreement on the correct LNAB before a merge is completed.
When the profile is historic or has been demonstrated to be a key or gateway ancestor for many and we can include it in a project, then we often Project Protect the Profile, PPP, such as this one. This ideally keeps the LNAB protected from being merged away.
PPP merges should definitely be discussed, especially if the PPP LNAB is the one that needs to be changed.
Mistakes happen however and we correct and move on.