There are plenty of examples on the net of standing PM photos. Not sure what credentials the author of that site has, but I think they should have researched more fully as it obviously is possible. I would never rely on one source anyway before I formed an opinion, and I've researched this issue many times over the years as it often comes up on the board (which is why I knew about the rigor not being permanent in case you're wondering

). As Carol says, you can never be 100% certain, but to both of us, this looks to be a more obvious example.
That site even has an example of child standing being held by someone behind a curtain, albeit a lot more obvious than in Carol's photo.
The images of the "photoshopped"

PM photos on that site are grotesque and an affront to genuine Victorian PM photos that were taken out of love and to provide solace to grieving families. I don't think any with an ounce of common sense would seriously consider these monstrous pics were used to for grief purposes.
There is also a shadow just below the deceased child's dress in Carol's photo which is intriguing and could be part of the stand.
Caz