thanks, I think I found a good solution.
Problem left is that if you open the child, then the price is again displayed. Grummel, grummel
fu php and their sloopy variable types. if ($bla=='0') is true for 0.00, okey lets do it with strcmp(), fu... the same
But should be managed now
delete a price to make a null price,.... if you want to overwrite the parent with a 0 price then use 0.0.
new c version is this evening. you was the last fix.