The weld log will only show the welds that are in the pack. You can edit the welds and add or edit data, but not add or remove welds. To add or remove welds from a work pack, check this article:
Revise a Work Pack.
Please read this article about editing and saving changes to welds, as the functionality is the same here as in the weld log, except that the advanced search to view and edit locked welds is available only through the weld log -
Weld Log.