adding REF_ROW to behavior

[jokaa]

Dear All,

In my application I have (training) Sessions to which the team members can apply. The app stores these as related attendances:

I can also archive these sessions, which moves the session to the "Archived sessions". To achieve that I created 2 actions, 1: to create a copy from "Current Sessions" to the "Archived Sessions", 2: to delete the session from the "Current Sessions" once I click on "archive".

What I would like to achieve is to have the related attendances shown on the Archived Sessions as well, however, on the behavior/action I am not able to add that row to the action which copies the session's details to the "Archived Sessions":
So this is the Ref_Row I would like to copy as well:

But there is no such option in the copy action/behavior:

This is how an archived sessions details looks like now:

I would like to have the related attendances show in the "Archived Sessions" part as well. Is there a way to do that?

If it can be completed with a slice, I would also be interested in that option (I tried it with a slice too, the slice gathers the Archived=YES sessions into a slice with all the information, however, the archived sessions are not removed from the Current sessions in that case, hence I went with this copy+delete behavior instead but with this solution the I cannot see who attended the archived sessions).

Sorry for the long post, thank you in advance for your help!