先搞好关系吧

首先不能理解你公婆为什么不愿自己住，按理说这种老人有一定的经济实力，我父母也是来加20+的老移民，他们是坚决反对和我哥全家一起住的，但喜欢住的近，彼此有个照应。I think your in-laws will buy a house of their own eventually but since you started the conversation, they couldn't take it too well. ( In their mind you want to "kick" them out). It doesn't matter who (you or your hu*****and) suggest it they will feel offended anyway. The reasons why they still live with you as I figured: 1. They love the grandkids too much that they can't image not seeing them everyday, the kids are probably small and when they are bit older they are not as "cute" as they are now, by then your in-laws might want to back up a little. 2. They do want to help his son's family and they feel more secured in case of emerency, you have to admit having two more people at the house does provide some convienience and extra help even it comes with some negetive outcome. 3. They are very very carefuly when it comes to invest their hard earned money on purchasing the right property, I am sure they want to live very close to you if they decided to move out.

我建议你暂时别提让他们买房和你爸要来的事，关系先缓和一下，你既然生性随和，就别再为孩子的事儿和老人们吵了，隔辈亲，让他们不惯很难，你严你有原则就够了，孩子是什么样，归根到底和父母的管教有关。在缓和的同时随时留意你家附近在卖的房子，在关系融洽的前提下，不经意地提出来，让你老公带他们遛弯时“顺便”逛个open house，一定让他们感觉到你们也喜欢住的近，他们看孩子也方便，你们照顾他们也方便。也可以提出支持他们一些钱已感谢他们这段时间对你们和孩子的照顾。 Good Luck!