@AbhishekAP

we cannot use this function directly. Since you want to check the logic inside when only, you can take below mentioned approach: 

Create a DataPage of type page. (Use some property (say ValueExist) which will return true if value exist in the embedded pagelist else, false) - Use this data page in the when rule

Use a DT as a source. In DT

1.  set ValueExist as false

2. For Each Page In -to loop over first Page list 

    2.1 when IsInPageList(PropertyValue,Property,PageList2).

          2.1.1Set ValueExist to true

- You can also parameterize the property values to make it reusable