SYMPTOM:
The "Merge" option is missing in conflict resolution for "Users and Groups" in Strategy Object Manager 9.4.x as seen below:

However, the following is stated in the online help:
<Online help>
Merge: Applies only to users and groups. The privileges, security roles, groups, and Distribution Services addresses and contacts of the source user or group are added to those of the destination user or group.
CAUSE:
This is a known issue with the Strategy Object Manager 9.4.x online help. The "Merge" option works in the same way as "Use Existing".
ACTION:
Currently this issue is being reviewed by Strategy for a potential code fix on an upcoming Strategy release. Use "Use Existing" or "Replace" accordingly.
The Strategy Internal Reference Number for the issue discussed in this technical note is 947098.