Hallo R.Brahmankar,
thank you for the answer. However, it does not solve my issue. I am aware of the note you mentioned, but it covers only the issue when the provided PRODUCT_ID was not correctly supplied (or reflected by the standard coding due to bug in it) during the change of the product.
What I am explicitly asking for is creation of the new product. Change part is just working fine for me. As mentioned in my original post, the issue is that the standard coding is not able to distribute the GUID (which is created for the new product on the fly) to the EXTENSION_IN data the same way as it's done for the other table parameters.
Any comments on this are highly appreciated
BR
Michal