I'd say that both sentences in the first set seem to work. However, I'd leave out "they say", unless it is absolutely necessary to leave it in. If you don't need it, you could just say: "Bequests are the money or property belonging to someone that, after their death, will be given to other people." For the second one - I'd leave out the "that they say" parts as well and have it read: "Bequests are the money or property belonging to someone, that they give to other people after their death”. If it's not possible to leave out "they say", then I'd go with the second choice. **I felt like I needed context for your question because I wanted to determine the importance of the "they say" is in those sentences.

Hi Fernando, In the first example, no THAT. THAT is wrong in this case. In the second example, no THAT sounds better; but you could put it in. The THAT is implied even if you don't say(write) it. While this would make the sentences grammatically correct, they are awkward sentences. Better sentence: A bequest is money or property that someone leaves to someone else after they die. (or even simpler, but more technical: A bequest is money or property that a decedent leaves to a beneficiary in a Will.)

Without the second "That" "Bequests are the money or property belonging to someone that they say they wish would be given to other people after their death” Although the above sentence is correct, it is somewhat awkward. A more elegant sentence would be... "Bequests are monies or properties a person wishes to be given to other people upon their deaths" 😊😊