Inline Add rows after 10 rows a new Custom row

Hi all,

I am building a project and i want to Add 1 new custom row after 10 Inline Spreatsheet mode rows.

I dont know how to start, can you point me in the correct direction?

Example:
Insert Custom row i insert in the DB "Orders"
I add inline Spreadsheet mode - Row 1 ...
I add inline Spreadsheet mode - Row 2 ...
I add inline Spreadsheet mode - Row 3 ...
I add inline Spreadsheet mode - Row 4 ...
I add inline Spreadsheet mode - Row 5 ...
I add inline Spreadsheet mode - Row 6 ...
I add inline Spreadsheet mode - Row 7 ...
I add inline Spreadsheet mode - Row 8 ...
I add inline Spreadsheet mode - Row 9 ...
I add inline Spreadsheet mode - Row 10 ...
Insert Custom Row with my own data automatically.
I add inline Spreadsheet mode - Row 21 ...
I add inline Spreadsheet mode - Row 22 ...
I add inline Spreadsheet mode - Row 23 ...
I add inline Spreadsheet mode - Row 24 ...
I add inline Spreadsheet mode - Row 25 ...
I add inline Spreadsheet mode - Row 26 ...
I add inline Spreadsheet mode - Row 27 ...
I add inline Spreadsheet mode - Row 28 ...
I add inline Spreadsheet mode - Row 29 ...
I add inline Spreadsheet mode - Row 30 ...
Insert Custom Row with my own data automatically.