If you are looking for textual evidence regarding this question, I would first start looking in chapter 6. This is the chapter that has the residents going through the Westing will and finding out the rules to the Westing game. Rule number 8 explains that the potential heirs will be paired up with one another. Chris is paired with Deere, and Deere is not happy about it. On the other hand, Chris is thrilled. He is paired with a member of "the outside world." It is his chance to be treated like a fully functioning member of society instead of the sick brother of the family.

As the reading continues, everybody learns in rule number 9 that each pair will receive a check for $10,000. Each member of the pair must sign the check in order for it to be cashed, and we learn in chapter 14 that Chris does not want to sign the check.

Chris knows that once the check is signed and cashed, Deere will take his portion and stop visiting Chris. Chris wants to continue playing the Westing game with Deere. Chris wants to be a valuable member of the team, and Chris really is a valuable member. His powers of observation are well honed, and he enjoys Deere's visits in order to pour over their clues. Chris wants Deere to keep visiting and keep playing the game as a teammate.

His partner would have to visit him a next time, and a next time, as long as he didn’t sign the check.

“Now, about signing the check,” Denton Deere said.

Chris shook his head. No.