For people, use consenting images with similar clarity and avoid presenting the composite as proof that an event occurred. For products, compare outlines and labels against the source. For historical or documentary work, retain the originals and label the generated composite.
A role ledger improves results: Image 1 supplies subject A, Image 2 supplies subject B, Image 3 supplies the room, and the written prompt controls wardrobe and camera. If the result fuses faces or swaps products, reduce the number of references and rerun before adding style.
Choose a deterministic collage when every source pixel must remain unchanged. Choose generative blending when the subjects need to share one perspective, light, or environment; use the group-photo path and role-based prompts to control the composition.
This distinction prevents unnecessary cost. If you only need two images side by side, use a layout editor. If you need one shared scene, expect reconstructed pixels and review the result against every source.