How to tie the dates of two items together
When creating your timeline, you may wish to tie two items together that occur on the same date. This is a helpful mechanism as it means that if you move one item whilst creating or editing your timeline, then the other will move with it. The best way to tie these two items together would be to create a constraint.
To do this, select one of the events, and go to the constraints tab in the Inspector.
Click on the + button next to 'Date Constraints'. Then, create a constraints where the 'Start' 'Equals Start Date' of another item. Here, we have used an example where 'MacQueen drugs Mr. Ratchett' is being tied to 'MacQueen talks politics with Colonel Arbuthnot'.
Resolving A Constraint
When you move either of these items, you will see in the Inspector and your Timeline view that the constraint has been violated. Depending on your Automatic Date Adjustment setting, when one of the items is moved the other will either automatically move with it, or the constraint will show as violated.
Ensure that you have 'Resolve Constraints and adjust children' selected for the 'Automatic Date Adjustment' option in your 'Settings' window, as this will mean that whenever you change a date, or move an event, the other will move with it.
Alternatively, you can resolve this constraint manually. You will do this by going to the Inspector and click the 'Resolve' button. When you click 'Resolve' you will be given three options, as pictured below:
If the date you have moved the selected item to is correct, then select 'Move other item to match selected'. Or, if moving the item was a mistake and you wish for it to be placed in the original spot, where the other item on the constraint is, then click 'Move selected items'.
For the purposes of this example, we've used 'Move selected items', so that 'MacQueen talks politics with Colonel Arbuthnot' moves back to the same dates as 'MacQueen drugs Mr Ratchett'.
Once you do this, the constraint should be resolved, and items will still be tied together.