A multi face swap needs a separate identity assignment for each selected person. Check the detected faces and test people entering, leaving or crossing in a video before rendering the full clip.

Choose the people to replace
Upload the group scene and a clear replacement portrait. Detect the faces, then select the original person for the first assignment. Add a person for each different replacement, up to four. Leave people you want to keep out of the assignments.
Build a separate reference set for each person
Use 1–5 photos of the same replacement person and up to eight references of the original person per assignment. References can use different video frames. Start with Natural; compare Stable Video on a short moving clip. Previews cannot establish motion quality.
Preview, then review every face
Check the selected people in a free frame preview. For video or GIF, test a short moving clip before processing a longer file. Compare every person at full size, including bystanders who should stay unchanged. Preview success cannot guarantee every later frame will match correctly.
A batch face swap is a different job: processing several separate files. Multiple faces means several people within one image or clip.