As for me, I put my pictures into slideshows. I have a slideshow for each country's royal family, Romania, Sweden, Hesse, etc. For the Romanovs, since I have so many pictures, I have a slideshow for each individual of NAOTMAA. Olga's are split into 2 different slideshows, before and after she put her hair up. I have a slideshow just for pictures with all of OTMA in it, and a slideshow for Nicky with any of his children. It's intense. As far as siblings go, for the most part, whoever is the oldest in the picture gets it in their section, i.e., a photo of Olga and Tatiana would go in Olga's show, since she's the oldest. However, since my Russia shows are kinda crazy, there are exceptions. As I said before, if the photo has all 4 of OTMA in it, it goes in it's own separate show (However, if there are only 3 of OTMA, it goes in the oldest girl's show). If Nicky is in the picture with the children, it goes in Nicky's show, regardless of how many of the children are in the picture with him. If Alix is with the children, it goes in her show, unless it has all 4 of OTMA in it, then it goes in the OTMA show.
In the cases where there are more than one royal family in the same picure, it usually goes to the family that has the most members in the photo, except in the case where I have difficulty identifying them, in which case it goes in the show of whomever I can identify first. I know I have a weird system, but it works for me.