Relationship Links

Who can use this feature?

Task Owners, Assignees and Admins can add relationship links between tasks

Relationship Links in Aphex allow you to establish task dependencies, ensuring tasks are completed in the correct order. Whether you need tasks to start together, finish together, or follow one another, Relationship Links help keep your project on track and aligned.

Drawing Relationship Links

You can draw links directly on the Gantt - just click and drag from one bar to another. The link type is set based on where you start and end. It’s quick, visual, and often the easiest way to build out your logic as you go.

How to Draw a Relationship Link:

Hover over the Predecessor Task Bar and click the
Click and drag from the predecessor to the successor
Release the mouse to automatically create the relationship.

Link Type and Direction

Direction

Visual

Explainer

Start > Start (SS)

The second task starts when the first task starts.

Start > Finish (SF)

The second task finishes when the first task starts.

Finish > Start (FS)

The second task starts when the first task finishes.

Finish > Finish (FF)

The second task finishes when the first task finishes.

Scheduling Behaviour

Moving a driving task will reschedule all dependent successors in the chain
Tasks won’t lose their link logic - rescheduling respects the original structure
Updates happen in real time as you adjust dates, add delays or drag bars on the Gantt

Linking Multiple Tasks

Checkboxes let you select multiple Tasks and build logic between them all at once. Set the sequence, adjust the link type & lag, and apply. It’s the fastest way to build out a full section of your plan.

To Link Multiple Tasks:

Hover over tasks and click
Click the Link icon in the multi-select toolbar
Choose the link type (SS, SF, FS, FF), add any lag if needed and confirm

Link Search

If the Task you want to link to isn’t visible, drop your link on the blue search icon. A menu will open so you can quickly search and select the right Task without changing your filters or losing your place.

Hover over the Predecessor Task and click the
Click and drag to
The Link Search Modal will appear. Use the search bar or filters to find the task you want to link
Select the task, choose the link type, and apply the relationship

Creating Links from a Specific Task

When you open a Task, you’ll see a full list of its linked Tasks including Link Type, Lag and Float/Driving. From here, you can make changes or add new relationships; no dragging or switching views required.

Adding a Relationship Link from the Task Panel:

Open the Task Panel for the task you want to link.
Scroll to Related Tasks and click
The Link Search Menu will appear. Use the search bar or filters to find the task you want to link.
Select the task, choose the link type, and apply the relationship.

Add or Remove Lag

Lag lets you add a space between linked Tasks, helping account for handovers, wait times, or real-world gaps without shifting tasks manually. As you adjust Tasks, Aphex gives you a quick visual cue showing how much lag you’ve just added or removed.

Add Lag to Relationship Links from the Gantt:

Use the Task Bar, or Start and End properties to edit the dates of the successor Task
The Lag Change Indicator appears, showing the number of lag days added or removed

Add Lag to Relationship Links from the Task Panel:

Open the Task Panel for the Task you want to link.
Scroll to Related Tasks and click into the Lag field and enter a value

On the Gantt, click a Link Line
In the Link Modal, click into the Lag field and enter a value
Select to apply the Lag change to the relationship

Lag Rules

The Predecessor Task Calendar is used to determine lag when added to a relationship link
When drawing Links on the Gantt, Aphex automatically applies zero-day lag, snapping the successor to come immediately after the predecessor
Hold Shift while drawing the link to keep the existing gap - Aphex will automatically calculate and apply the right lag to preserve the spacing between tasks
The Lag Change Indicator will be visible on the Gantt for a few seconds after the change is applied

Identifying Driving Tasks

Each relationship between Tasks shows whether it’s Driving or how much Float it has. A Driving relationship means the predecessor has zero float - any change to it will move the successor. Links with float display how much flexibility exists before the successor is affected. These values update automatically as Task dates, link type, or lag change, helping you see which parts of the schedule are fixed and which still have room to move.

To reveal Driving Tasks & Float from the Gantt:

Click any relationship link on the Gantt - single or multiple
In the Link Menu that opens, Driving Tasks are marked with
Links that aren’t driving display their Float Value

How Driving Tasks & Float are calculated

Float is the amount of time a predecessor task can move without delaying its successor
It’s calculated automatically using the start and finish dates of both tasks, the relationship type, and any lag that exists between them
When Float = 0, the predecessor is considered Driving - any change to it will immediately shift the successor’s dates
When Float > 0, the predecessor is non-driving and has flexibility before it impacts the successor
Float and Driving values update dynamically whenever task dates, relationship types, or lag are changed

Example

Predecessor task finishes on: 1 September
Successor task starts on: 6 September
Lag: 1 day
Assume all days are working days

Step-by-step:

Days between 1 Sep and 6 Sept (inclusive): 5 days
Float = 5 - 0 - 1 = 4 days

The predecessor has 4 days of float. It can finish as late as 5 September without delaying the successor

Editing & Breaking Links

You can edit or break existing relationship links at any time to update or remove connections between Tasks.

How to edit an existing Link:

On the Gantt, click a Link Line
In the Link Modal that opens, you can either:
- edit the Link Type (FS, SF, FF, SS)
- edit the Lag
Click to apply edits to the relationship

Breaking Relationship Links:

On the Gantt, click a Link Line
In the Link Modal that opens, click Remove Link

Understanding Scheduling Behaviour

Understanding scheduling behaviour helps you predict how linked tasks behave when dates change based on whether they're Planned, Promised, or Done. It’s the key to controlling movement, Ripple Status, and Progress Updates in your plan.

Successor is Planned:
- Both tasks reschedule freely.
- Successor follows any changes to the Predecessor.
Successor is Promised or Done:
- Successor won’t move.
- Only the Predecessor shifts.