So Batman, Superman and WW were active during WW 2 as part of the JSA?
Obsidian and Jade are usually depicted as young, but older than Dick's generation. Although Jade is sometimes depicted as younger than Obsidian, either Dick's age or slightly younger.
Stargirl is always depicted as the same age or younger than Tim's generation.
Dinah is always depicted as being a lot older than Dick's generation but relatively young(late 20s to mid 30s).
Honestly, I'd worry about the next generations and their ages much later in the process.