A flowchart can look connected until one box moves and leaves its arrow behind. The important relationship is between the two objects, not between their old positions on the slide. Establish that relationship before polishing the line’s appearance.

Use a copy of the diagram and start with two boxes whose connection is unambiguous. Label their roles and decide the direction of the relationship. For a larger process, keep a short list of which box should connect to which destination, including any exception route.

In Keynote on Mac, add a curved line from Shape. Drag one endpoint until it snaps to the first object, then snap the other endpoint to the second. Connected objects remain joined when moved. With the line selected, Format, Arrange offers Straight or Corner, and the Connection section’s Offset Start and End values adjust the endpoint spacing.

Line appearance is controlled separately in Format, Style, including thickness and endpoint shapes. An arrowhead communicates direction visually, but it does not establish that the two chosen boxes represent the correct process relationship.

Test each attachment rather than only the line

Move the first box a noticeable distance and inspect its endpoint. Then move the second box. The line should follow both attachments. Undo the trial movements after confirming the behaviour, or keep the new positions if they improve the approved layout.

If an endpoint stays behind, reconnect that endpoint deliberately. Zoom in enough to distinguish a snapped connection from a line that simply ends near the box. Avoid compensating by dragging the line back into place after every layout edit.

Now inspect the whole route. A technically attached connector can pass through another box or make an arrow direction ambiguous. Adjust the arrangement or corner geometry so the audience can trace the intended relationship without guessing at crossings.

Check topology after rearranging the diagram

Compare every connection against the process list, especially after moving a branch or swapping two boxes. Read the flow from the starting node to each possible ending. Ask another person to follow one normal route and one exception route without using your editing notes.

Finish by viewing the slide at the size the audience will see. Confirm that arrowheads, gaps and labels remain legible. Keep the editable connected diagram so future spacing changes can preserve its relationships instead of rebuilding lines from remembered coordinates.

Reference: Apple: Keynote lines and connected objects.