The only one which sticks in my mind is the one I asked about in the above post of skinny Romanov sister - I cannot remember what the other photos were at all.....From comparing my memory with what I've seen of existing photos , it was Olga or Tatiana
Do you remember anything else about the photo you're looking for? Was there more than one person in it? Were they sitting or standing? Indoors or outdoors? Dressed in light or dark clothes? "Skinny" is very little to go on, and also a rather subjective feature.
It's not unusual for pre-captivity photos to be mislabled as taken in Tobolsk or Ekaterinburg. For example, there's a couple pictures of Nicholas II in a wheelchair that are often captioned as "the tsar at the end of his life in Ekaterinburg," when in fact they were taken almost 20 years earlier in Livadia. There's also a photo of the grand duchesses looking out the window of the governor's house at Stavka which is almost always mislabeled as the governor's house in Tobolsk. So limiting yourself to captivity photos may not unearth the image you're in search of.
This is the only photo that comes to mind based on your description, though Maria is the only one who looks noticeably thinner than usual to me. It was taken early in captivity -- while the girls were convalescing from measles at the Alexander Palace in the spring of 1917.
