Q) Do we need to keep the kesuboh in our house specifically? And what happens when we travel abroad? What would happen if the kesuboh would get lost or misplaced?
A) There is no source nor reason that the kesuboh needs to remain in the house of the married couple (Mishpot Hakesuboh 59:3). Some have the custom of giving the kesuboh to the wife’s mother for safekeeping.
Regarding travelling abroad, there is no reason for the kesuboh to be taken with on the trip; in fact it would be safer for the kesuboh to remain where it is, as often during travelling one’s possessions can get lost or damaged (Mishpot Hakesuboh 59:7).
The Shulchan Aruch (Even Ho’ezer 66:3) rules that if the kesuboh is lost, a replacement kesuboh needs to be written immediately. This is because it is forbidden for a couple to live together even for a short amount of time without a kesuboh.
However, if the kesuboh was originally placed in a safe location, and has now been misplaced, if there is no reason to believe that anything has happened to it – i.e. there has been no burglary, fire or suchlike, it can be assumed that the kesuboh is still in existence (and just misplaced) and there is no need to rush to write a replacement kesuboh (Mishpot Hakesuboh 65:6).
If after a thorough search of the house the kesuboh is declared missing, or there is substantiated reason to suspect that the kesuboh has in fact been destroyed or stolen, then a replacement needs to be written immediately (as per Shulchan Aruch and Remo ibid.).