Hi madej -
The understanding of Russian silver and its marks is a constantly ongoing process. The existing textbooks are partly outdated or incorrect, new findings are not yet documented. Collectors that are internationally networked and exchange about existing pieces come to interesting results. You can participate or ignore the new findings! A present object consists not only of a brand but also of a certain style, quality and craftsmanship. All these things should be taken into account ....
You only have 1 object of this manufacturer - others have 20 different objects of him - with marks that have different catouches - but all are from the same manufacturer - reread above.
Example:
I already showed you ee in a rectangular cartouche. Here is one rectangular with cut corners - same maker.
A salt throne (PL does not mention the production)...
Now you can start to think, combine and investigate - or wait and hope that someone else solve your problem.
Regards
Goldstein