IMO I doubt such a situation would ever get to court. In fact if it got to that stage, you’ve lost.
I would view such a clause as an ‘intention of wishes’ or even a negotiating tool but, again, if it became fractious (with the family) you’ve lost.
IMO (I am no lawyer) if the family are against you nothing is likely to work in practice. If it really matters take out a lease or arrange a usufruct. I did the latter almost 20 years ago just to protect my short-term position. My name appears on the chanote in the same way that a mortgagee’s name might appear on deeds in the west. That means that the property cannot be sold from under me….well it can, but it would be sold with my rights remaining - in the same way a sitting tenant retains their rights if a property is sold.
The law in Thailand is fine and, unlike some Farang think, it does not favor Thais. However, especially in rural areas a sort of ‘jungle law’ can prevail. If family etc want to make life Hell then the law will still protect your rights - but your life will still be Hell.
I have seen several (non estate related) cases where Farang expectations of theory are not matched by reality.
