Please give me some advice! Thanks.

We usually see my in-laws once a week on Sundays after church. They do spend a lot of time with my sister in law who stops by all the time. My sister in law is going to Vegas this weekend and leaving her kids with my in laws. My in laws mentioned they are taking them to the movies but didn’t invite us. Should we invite ourselves over to their house like my sister in law does or wait until they invite us?