Most people add a symbol between two words, just like upside-down braces, so words should be added to the symbol.
After a calligraphy work is typed, you can indicate the place where a certain word is missing in the inscription, and then indicate the source, time and name. It is normal to miss it. There are omissions in calligraphy works, and the remedy is to add them to the right of the missing words. If there is any omission in the process of calligraphy creation, it can be added directly in the gap between lines at the left end of the blank.