Arrivis, you can't tell me you weren't expecting these jokes when you posted here.
However, if you have established a game world where intelligent humanoids are as capabale of freewill as PC race, then I can't see why a group of good adventurers wouldn't feel morally obligated to raise the orphaned young of a dead ally. So ignore the nay-sayers, kobolds get a bad rap. If we were talking two elf children here no one would balk.
In serious answer to your question, I would consider the following:
Hatchlings (1day-say 6 months): 1 hp, and no other real stats. Your PCs are of a level that anything that might harm the babies can be dealt with unless they do something like take them into combat. If they do something like that its all a matter of DM fiat anyway with such weak beings.
Children (6months -2years): give them another hp and double the penalty for being an adolecent as found in the PHB (mine is not readilly at hand) applied to a standard kobold.
Adolecent (2-3 years): If I recall correctly there are stats for adjusments of adolecents in the PHB, just apply them to a standard kobold. This is the point where the little ones might actually be fun as plot devices. They run off, kidnapped by an evil wizard who wants to use them as potion fodder, local kobold tribe wants to know why the pcs have taken their young and lodge a formal protest (with a threat of war) with the local officals, etc.
Adult (3yrs+): If I had kobolds hanging around with powerful PCs I would let them learn the skills of the PCs - allowing them to take a level in any class the PCs had. Now they are perfectly competent and able to either go out on their own or remain at the PCs HQ as jnr. party members charged with guard duty and other age/level appropriate tasks.
Since your party is near epic levels, you might even have the new 1st level Kobolds find some friends (more wards of the PCs maybe) to adventure with, and have the players switch between their godlike main characters off smiting Slaad Lords or whathaveyou and the weaker, and unusual, 1st level monsterous humanoid PCs. Could be fun.
Through out all of it you might want to have the PCs make periodic roles on whatever Knowledge skill (or maybe just Int/Wis/Cha to know what to do/how to do it/and how to make an impression on their charges) you think most appropriate to raise not only healthy buy GOOD kobolds.