How to solve the problem, with any changes in the parent product, throw off the customfield from the child products?

Question

Joomla

There is a parent product, and a number of some child products.
Each child product has a number of custom fields.
There was a problem, when saving any changes in the parent product, let's say the description, in the child products are updated too. Where in the code can I fix this problem. I've looked all over the model and still can't find it.