Don't know how I missed this one from the 6th Sept.
You can do what @Leo suggests but ONLY if the cables to the hob and oven are also at least 6mm sq..
I suspect that they are only 2.5sq., in which case they MUST be changed.
May be easier to loop from one to the other rather that trying to get two 6mm into a block connector.
Imperative that 6mm sq. cable is used and all connections are tight. Check/re-tighten after a week.