I think Smguinnip has a good idea, although in practice it might be difficult, or at least tedious, to get one strand loose from each bundle. If it works, the end result should be no different that padding the loops of a 14 strand string with two short strands to make 16 strand loops. In fact, I do that on purpose when I make a string, so the loops are a little easier on the bow tips. In fact, I may have to try that on purpose on the next string I make to see if your method is easier to do and comes out with a better string than weaving in two short strands to pad the loops. Of course, I’ll cut the two midsection strands out before I twist the midsection.