In contrast to the classic UI, Agent Workspace does not have the option of cell editing, but you can select multiple records and edit content simultaneously.

There was a question in the community whether this feature would also be available for Related Lists.

After playing around for a while I have now found a solution and with the help of the following instructions you can also implement the Edit button for Related Lists.

	Go to table sys_declarative_action_assignment (don't use any navigation item!)Open "Configure" > "Data Policies"
	Disable the only available data policy "Make Action Model field read-only ..."
	Back at table sys_declarative_action_assignment add column "Action Model"Locate record with Action Label = "Edit ({{count}})" an open it
	Create a copy of that record by choosing "Insert" at context menu
	Back at table sys_declarative_action_assignment change value at column "Action Model" of second "Edit ({{count}})" record to "Related List"
	Now there should be an "Edit" button at related lists.