I think what your trying to do here is go around the law by saying its not yours cos your not tending to it and its just growing naturally in the wild. All the person is trying to do is what a child would do and say "Thats not mine". The plant is still illegal (Section 17 of the Misuse of Drugs Act 1977) , the cannabinoids on the leaves/buds are still illegal (Section 27 of the Misuse of Drugs Regulations 198
and the Gardai will still chop it down and destroy it, and if they suspect its yours they'll try their damn hardest to prove its yours.
Just grow it remotely and dont tell anyone, if anyone is able to see your outdoor plants your not planting them in the right place IMO.