Modifying an arc in GAMBIT?

Jake

Hello, I am currently trying to modify an arc that was previously created by another person.

Problem is, I don't know where that person referenced to create the arc, origin or vertex, etc. (no longer in contact with the person by the way).

All I have at this point is, that the where the arc should start and end. I have no idea where the origin is or what vertex were used.

Is there any way to figure out how the arc was created so that I can modify it?

Thank you.