@Victor_Pishtovkolev - Prashan is correct. There are certain required tables for Process Mining to work. Event_log is one of them for the Custom Template. More details are available here - Process Mining - Data models
The reason you don’t see it in Oracle P2P app is because, in that template the required table name should be purchase_order_item_event_log. Some templates have a customized name for the event_log table.
You can customize your event_log table as much as want, it just needs to be named event_log and contain the required fields listed in the linked document above.
Lastly, we are working on a new feature for supporting multiple processes in a single app. It is in a preview and if you think it will align for your needs, please reach out to @Martijn_Wijffelaars.