If you have vv files, you can merge those files without any problem because answer options appears as a result (inside the table) and not as a row or column label.. In other words adding and removing answer options is not changing the table structure...
The problem is that the final data analysis for this question may be unclear if an answer option was not available during all the time.
/!\ If in addition of removing answer options you have canceled another question, remember that you have to edit (adapt) the first vv file, removing the corresponding column, because the 2 first lines (headings) of the vvfile have to be 100% similar to be marged & reimported. More info
here.
Ben/