Not sure if understood you well.
The field in the slicer shall come from a dimension table, that table shall have relationships on a primary key to both of your datasets. Or the field in the slicer can sit in Dataset 1 but Dataset 1 shall have one to many relationship filtering Dataset 2.
If you want to syncronize the slicers, so whatever you choose on page one is selected on page 2, then View-Sync Slicers, Select the Slicer you want to sync and tick it in the corresponding box, hope thats answers your question.
