To dissolve an activity, you select the activity and then choose Edit, Dissolve.
Dissolving an activity removes the dissolved activity and joins the dissolved activity’s predecessor and successor activities as well as possible to maintain the project’s network logic, as explained here. You cannot dissolve an activity unless it has a predecessor and successor.
When an activity is dissolved, relationships are made as follows:
- The first half of the relationship between the immediate predecessor of the dissolved activity and the dissolved activity is used as the first half of the relationship between the predecessor (of the dissolved activity) and all successors that had a relationship with the dissolved activity.
For example, say that Activity A is the immediate predecessor of Activity B, that Activity A has a Start to Finish relationship with Activity B, and that Activity B is to be dissolved. When Activity B is dissolved, all of A’s relationships with B’s successors (with which B had a relationship) must begin with Start.
- The second half of the relationship between the predecessor (of the dissolved activity) and each successor that had a relationship with the dissolved activity remains the same for each successor as when each was linked to the dissolved activity.
To continue the previous example, say that Activity C is the immediate successor of Activity B, and that Activity C has a Finish to Finish relationship with Activity B. As Activity B is dissolved, the second half of its relationship to C (C’s end of it) is used and combined with A’s first half of its relationship with B, giving a Start (from A’s side of the A to B relationship) to Finish (from C’s side of the B to C relationship) relationship.
The same principle applies to any other successor activities to B.
So, for example, the following activities have the following relationships:
Activity A is linked to Activity B using SF
Activity B is linked to Activity C using FF
Activity B is linked to Activity D using a FS
Activity B is linked to Activity E using SF
Activity B is linked to Activity F using SS
When you dissolve Activity B, the following occurs:
Activity A is linked to Activity C using SF
Activity A is linked to Activity D using SS
Activity A is linked to Activity E using SF
Activity A is linked to Activity F using SS
By default, any lag applied to relationships with the dissolved activity is removed and the new relationships created have zero lag. However, you can select Retain lag on the Calculations tab of User Preferences if you would prefer to keep the lag applied to predecessor and successor relationships when you dissolve an activity. If you choose to retain lag, the lag from the predecessor relationship is added to the lag from the successor relationship and applied to the new relationship.