Indeed I found it in mmBusinessObject.cs... and this method HookPreSave(DataTable dt) is called only from

PreSaveProcessing(DataSet ds, string tableName) - even located in mmBusinessObject.cs

I made some "research" into this... (BTW - I'm using the MM .Net 3.5 - latest updates).... and it's true...

the HookPreSave is not called for the child objects !!!

Calling Kevin for Q: Is this by intention?...

-----

In mmBusinessObject.cs -

function PreSaveProcessing(DataSet ds, string tableName)
{
if (!this.RulesCheckedByParent) //... on line 5111
{
...
Result = this.HookPreSave(ds.Tables[tableName]);
.....
{
return true;

So when the child objects are called for saving, the Rules has being checked by parents, RulesCheckedByParent is set to true and the HookPreSave is not called at this time...