Are newly gained items considered Bequests in Haunt 94: Last Will and Tournament?
From the secrets of survival tome:


  Each hero draws an item card, then each counts
  his or her total number of item cards and omen
  cards that can be traded or stolen. (A card that can
  be traded but not stolen, or vice versa, counts. For
  example, the Armor and Blood Dagger count, but the
  Bite doesn’t.) These cards represent your Bequests,
  which will change as you gain and lose cards.


Especially that last part is interesting for your question: These cards represent your Bequests,
which will change as you gain and lose cards

This means that every omen and item card which fits the previous description you gain will become a bequest, if you lose one they will stop being a bequest.

for other confusions: read this