Possibility of using cascading replication with slots?

Hi,
We have 2 clusters at different places, let’s say 1st cluster named is X and 2nd is Y.

X has 3 nodes(1 primary, 1 sync, 1 async)(inside cluster nodes are connected with replication slots)
Y has 3 nodes (2 asyncs )(inside cluster nodes are connected with replication slots)

X’s sync replica is connected to Y with cascading replication using streaming method “without slots”.

The question is that Is there a way to change this cascading replication connection between clusters to physical slots?

Running on postgres 9.5.

Thanks for any answers.