A method, by a multipath control entity, to control a transmission of a user data plane stream between a mobile entity and a proxy, wherein the user data plane stream is exchanged between the mobile entity and an application server connected to the proxy. In a split decision, it is determined that the user data plane stream is split into at least two stream parts and over which of the supported network technologies each of the at least two stream parts is transmitted between the mobile entity and proxy. A multipath connection module in the mobile entity is informed in a first control message which stream part is transmitted by which network technology in accordance with the split decision, and a multipath connection module provided in the proxy is informed in a second control message which stream part is transmitted by which network technology in accordance with the split decision.