关于房屋买卖中的determination of agreement

同卖方签的合约包括买方有30天的due diligence period, after due diligence period卖方就keep2.5万的earnest money，卖方可以免费住两个月after settlement.

在due diligence period, 买方要求卖方签一个agreement 包括卖方要签lease with new owner and leave $1000 security deposit. 卖方拒绝，事情就一直拖下来，现在过了30天的due diligence period, 卖方要keep earnest money.

buyer's agent 说合约有一句话the agreement of sale is pending on the buyer receiving the seller property disclosure. 买方从没有收到过卖方的property disclosure. 想以此为由walk away. agent 说要双方签一个determination of agreement。 买方担心的是根据那句话这个agreement of sale 是无效的。 如果签了determination of agreement，会不会就变成买方default承认agreement of sale是有效的，才有之后的determination. 谢谢指教！