Welcome to Seamly @hayleyneil!
I think you are saying that you made a curve, & then made a line to help control the curve. Since Seamly2D reads the items on one drafting block in the order in which they were created, the lines does not yet exist at the creation of the curve, & so it cannot be based on it. So there are two solutions:
- Delete the curve & remake it after you’re done creating its guidelines.
- Use the History window to virtually time-travel & create the lines before the creation of the curve. When using the time-travel it is recommended to save-as first, in case you inadvertently create a dangerous time-paradox.
- To use time-travel: open the History window, move the arrow marking your current location in time to the place it needs to be, perform the actions, move the arrow back to the future, close the History window.
I hope that helps! If not, @Grace is an experienced Time-Lady, & so can probably explain the use of the History window better than I can. Also @Douglas can probably better explain why time-travel, & what the chances are that eventually it could happen safely out of sight.