Nobody can tell you anything without seeing it. Provide a reference screenshot and tell us what version of AE you use at least...
I just see one person but if another walks in front of the reflective frame the technique is the same. Here's what you do:
- Stabilize the shot if it has any camera movement at all so the frame doesn't move. This may require stabilizing both scale and rotation. Name the layer "stabilized"
- Duplicate your stabilized layer and mask out the reflective frame so you can use a blend mode to create the reflections on your replacement image and name this layer "track matte"
- Use Rotobrush to cut out the people on the reflection layer then invert the matte so that there's a hole in the layer where the people are
- Add your replacement image to the composite below the "track matte" layer
- Duplicate your track matte layer and rename the top copy "reflection"
- Set the "track matte" layer as an alpha track matte for the replacement image layer
- Adjust the blend mode of the reflection layer to overlay or screen, adjust the opacity and add the curves effect to adjust the reflection on the replacement image
- Add a null and name it "destabilize"
- Apply this animation preset to the "destabilize layer" which will add expressions that reference the anchor point, scale and rotation property of the "stabilized" layer to the null's position, scale and rotation
- Select the stabilized, replacement image, track matte, and reflection layer then make the parent of these layers the children of the "destabilize" null using the parenting tool
This is the best way to build this composite. If the camera ls locked down then you can leave out step 1, 9 and 10.
For a more complete explanation of how to destabilize a shot using my animation preset and a null check out this thread:How best to motion track blurry footage
This page has some tips and tricks for making rotoscoping faster: After Effects Help | Managing and animating shape paths and masks
The Roto Brush may be perfect for this sort of thing. This page has some tutorials on using the Roto Brush: Roto Brush in After Effects