With the possibility of sharing access resources between mobile and non-mobile networks, the correct adherence to priority per traffic flow can become a challenge. In this paper, the dynamic allocation of transport network resources is explored through a drop-in Software Defined Network (SDN) controller and xApp. This controller updates priority rules within the transport network supporting an Open RAN (O-RAN) Alliance compliant architecture. The Radio Access Network (RAN) architecture considered separates Baseband Unit (BBU) functionalities in Central Unit (CU), Distributed Unit (DU) and Radio Unit (RU). The control plane messages are to be exchanged between each unit in an encrypted channel. As such, the transport network-aware control was implemented through a xApp and Near-RT RIC, and is done by identifying Data Radio Bearer (DRB)s per User Equipment (UE) and corresponding GPRS Tunneling Protocol User Plane (GTP-U) tunnels set between CU and DU. This work delineates the necessary control flow, from F1 Application Protocol (F1AP) control plane protocol to the subsequent SDN controller dynamic allocation to realise the proposed framework, and proposes the exposure of further information into the Service Models (SM) for the xApp. Finally, it is shown the xApp with the exposed TEIDs and ensuing flow setup through the controller.