Front row: BID Elin, JID Isar, BIDs Nami and Byuri
Some people combine all the sizes into one family with JIDs and BIDs being children to the much larger EIDs and SIDs. Problem is, the JIDs are waist-high to Tedros, and that's the height of a 4-6 year old, not a child of 8-10. Just to prove my point, here's a photo of my 6' son with my 4 and 5 year old granddaughters. They are waist-high. Taller compared to their Mom who is shorter.
My JIDs are definitely too old-looking to be children to the larger dolls. In fact Isar looks to be about the same age as Carina, just a lot smaller scale. Kyle and Asa look to be mid to late teens. BIDs come to the waist of a JID, so I consider them to be 4-5 year olds with my JIDs.
I just solve the scale issue by keeping my taller and smaller dolls separate. The JIDs and BIDs go great together, and the new KIDs just released by Iplehouse will fit nicely in between.