Perhaps the flagbearer is included because Strelets also has the wargamers in mind. Many rules demand a command set (officer, standard, musician) without regard for historical accuracy. But as Roger said, it can be utilized as a musketeer standard bearer, so not much is lost.

Thanks a lot to all of you. It's a great help.
Special thanks for the wonderful links.

Wish you all a wonderful evening and stay healthy.

Thanks Mr Schmitt & you are welcome.

You stay safe & healthy too.