Ball marker moved by another ball

[Ross61]

I was playing in a comp and on a green I marked my ball. Another player was a few yards further away. I asked if my marker was on his line and did he want me to move it. He said that it was ok where it was.
He then putted and hit my marker and flipped it over.
I was unsure if the marker had moved forward when it flipped, but the other two players did not know either. We agreed to play my ball from where the marker lay.
Should there have been a penalty incurred in this instance?

By the way, after hitting my marker the ball carried on and hit the 3rd player's marker that was the other side of the hole! Quite an acheivement I thought.

 

[Spuddy]

I was playing in a comp and on a green I marked my ball. Another player was a few yards further away. I asked if my marker was on his line and did he want me to move it. He said that it was ok where it was.
He then putted and hit my marker and flipped it over.
I was unsure if the marker had moved forward when it flipped, but the other two players did not know either. We agreed to play my ball from where the marker lay.
Should there have been a penalty incurred in this instance?

By the way, after hitting my marker the ball carried on and hit the 3rd player's marker that was the other side of the hole! Quite an acheivement I thought.

You have to replace your ball as close as possible to where it originally lay. In this case, as you are unsure as to the marker's original location then you just have to take a 'best guess' and go from there.