Q. See question above. Thank you for your prompt answer. I have also seen often in Kesuvos written specially by an artist or the Chattan himself that there is a considerable separation between the text and the lines for the signatures. Is that also permitted after the fact?

A. The concern of having a significant gap between the last line of text and the signature lines is recorded in Shulchan Aruch. (Choshen Mishpat 45: 6). The reason is to prevent forgeries, since there is enough place to add falsehoods. The space should be less than two lines. (Nachlas Shiva 2, Kesuva Kehilcheso p. 53).
However, some Poskim permit after the fact (Mishpetei Kesuvo p. 359, Kesuva Kehilcheso ibid.)

Horav Shlomo Miller’s Shlit’a opinion is that one should add an additional signature over the others, to reduce that space.

Rabbi A. Bartfeld as revised by Horav Shlomo Miller, Horav Dovid Pam, Horav Aharon Miller and Horav Chanoch Ehrentreu Shlit’a