Hi @aurel_e. I do not use Frame Generator that much, so I am not familiar with that little form showing in the image you attached, but I wander if you are familiar with the place within the Application Options where you can set up the naming schemes or things like Frame Generator stuff. It is in the Application Options > File tab > at the bottom is a button named [File Naming Defaults...], and when you click that, a dialog by the same name will open. Within that dialog are 3 tabs (Frame Generator, Tube & Pipe, & Mirror & Copy). Within the tab for Frame Generator, there are many places for you to configure how different things will be named by default.
To Customize Frame Generator File Names and Folder Structure
But if you already know about this, and it doesn't meet your needs, or maybe the form you are showing is a custom one, maybe the code at the following link may give you some ideas.
https://forums.autodesk.com/t5/inventor-ilogic-and-vb-net-forum/sequential-file-name-scheme-excel/td...
If that post is not helpful, there are several other similar posts on this forum which go into examples of custom naming schemes. Generally speaking, if the form is one that is built into Inventor, we do not have hardly any control over them, and can not easily interact with them. Often times those forms are 'modal', which means that any code you may have in an iLogic rule or VBA macro will be paused while it is open, making it impossible to interact with it from those types of codes. And when the form is not modal, it is still very difficult and complex to be able to interact with them. Sometimes we can attempt to simulate sending keyboard key strokes to the form using System.Windows.Forms.SendKeys.SendWaith() method, but that can be very risky, because it is 'blind' (doesn't know where it is sending the keystrokes), so if the 'system focus' is in the wrong place, those keystrokes may effect something else in your computer. There is a way to send a few specific types of data up to Inventor's session memory, that may work in certain specific situations to fill in expected built-in forms when they pop-up, but I don't know if that will work in this situation. It is at the following location:
ThisApplication.CommandManager.PostPrivateEvent()
...and here is the link to its online help page:
https://help.autodesk.com/view/INVNTOR/2022/ENU/?guid=CommandManager_PostPrivateEvent
Wesley Crihfield

(Not an Autodesk Employee)