Do it like in Rugby League. If the ref thinks it's a try but that there may be some other factor he passes it to the video ref who, if he can't find any reason to not award the try awards it, or if he finds an infringement doesn't award it. Conversely if the ref doesn't think it's a try but thinks he's got it wrong he says no try and passes it to the video ref to check whether the decision should stand. In both cases the video ref has the final say. The trouble with VAR is the ref being told by the control room that he needs to check something rather than the ref himself making the decision and passing it to the control room to confirm. In other words if there is a possibility of a penalty on the pitch the ref should be able to say that either he is pretty sure it is or isn't but needs confirmation, and the control room can then confirm either way.
