Certainly amicable settlement is always the best.
In the matter posted by you, it is strange that even the Sons have preferred not to spend from their own funds, on bedridden sick father.
Even daughter has not spent from her funds.
Instead funds were withdrawn from FDR of father and they have gone to the extent of taking thumb impression of bedridden sick father.
This gives fair hint that amicable settlement shall require effort.
Still amicable settlement should be preferred.