Yes, you can send a message to the rightsholder during negotiation.
When it is your turn to amend the offer please open the request by clicking on the Action needed tab and select the little envelope with the respective order number. You will then be able to submit a message to the licensor.
When it is not your turn to amend the offer please open the request by clicking on the Awaiting reply tab and select the little envelope with the respective order number. You will then be able to submit a message to the licensor.