I have been using KGTD for some time and I don't think it has this feature, but I think it would be useful.
The idea is that one item's due date is firm and the due dates for related items are set relative to the firm date, for example: two days before, two weeks before, three days after, three months after, etc. Then if the firm due date changes, the other related due dates change automatically. This would avoid having to change all of the due dates for the related items individually, which can get very time-consuming.
The repeating function doesn't do this if the related items are different actions.
The idea is that one item's due date is firm and the due dates for related items are set relative to the firm date, for example: two days before, two weeks before, three days after, three months after, etc. Then if the firm due date changes, the other related due dates change automatically. This would avoid having to change all of the due dates for the related items individually, which can get very time-consuming.
The repeating function doesn't do this if the related items are different actions.