Two good portraits don't make one believable photograph.
When people come together, it's not just the faces that have to be reconciled; the camera, scale, direction of light, color, depth of field and contact with the surface must tell a single story, otherwise the result looks like two cut silhouettes.
Choose Sources with a compatible camera
It's easier to combine two portraits taken from about the same height and a similar focal length, so if one person is photographed with a wide-angle camera on the bottom and the other with an eye-level long lens, their faces and bodies are subject to different perspectives.
Similar angle, visible shoulders, soft side light.
Different head rotation, but the same camera height.
Strong selfie distortion and hard light on the other side.
Growth is not determined by the height of the head in the frame
The scale depends on the distance to the camera and the position in the plane of the floor. First set a common eye line for people at the same distance, then check the shoulders, seat or table surface. Don't try to "align" shapes with simple stretching.
One light source explains both faces.
If these attributes diverge, the background will not save the composition; it is better to choose a different source or honestly bring one person's light to the common scene, preserving the natural volume of the face.
Contact creates looks, gestures and a common surface
People may not touch each other, but they need to be in the same space. The direction of their eyes, the position of the elbows on the table, overlapping shoulders and contact shadows link them together; a random hand behind someone else's back, by contrast, instantly gives off an assembly.
Request.Put two people at the same table by the window. Keep faces, hairstyles and clothes from references. Camera at eye level, same scale, soft light on the left. Elbows naturally lie on a table, arms do not overlap, there are slight contact shadows under them.
Build the image in four passes.
Match the camera and scale.
Check the faces separately.
Bring the light and color together.
Examine your hands, floors and shadows.
Before combining, evaluate four pairs of signs
Match the height of the camera, head rotation, light stiffness and face resolution. If there are at least three pairs that match, assembly usually requires less reconstruction; if one matches, first find a more compatible source or separately bring portraits to close light and scale.
As a result, you don't just have to check faces. You need your feet on the same plane, your shadows go in an agreed direction, the sharpness changes with the depth of the scene, and no contact between people creates extra fingers or intersections of clothing. Then take turns covering one person and make sure that the other person's appearance is not mixed with reference.
A strong source difference cannot be corrected with a single phrase.
Night photography and day selfies, profiles and frontal portraits, low and high resolution require reconstruction rather than simple assembly. Sometimes it's quicker to pick up more compatible shots than mask all the differences with generation.
Likelihood appears between people, not within each portrait.
A good composition preserves personalities and at the same time subordinates both figures to one camera, one light and one physical scene.