Conner should be allowed to age from the beginning and be made a Kryptonian/Human Hybrid just from the beginning.
It simplifies everything and it was never something what was really important.
Conner needs to finally become older than 20, so he isnt a teenager anymore...
I would say:
Clark: 35-37 (It doesnt mean anything, since he is Kryptonian)
Conner: 20-21
Jonathan: 10
Problem with the ages is that Jons age here wouldnt make much sense, since Conners first appearance and Jonathans birth would be close to each other and so Conner actually should be 25 when Jonathan becomes 10.
THREE BOOKS FOR CLARK????
ADVENTURE OF SUPERMAN: This can be a special Else-World Book which comes out once every year or so...
SUPERMAN: All the characters sharing one book??
Better solution would be:
SUPERMAN: Clark in the present with Jonathan, Lois etc.
SUPERMAN OF HAWAII: Conners Book
SUPERGIRL
SuperSons
This would actually be perfect:
Every character gets spotlight, different tunes, different locations etc. etc.
Conner is more important than Kara, given that he was there before her, he has the better feats (Gog,Doomsday,Superboy Prime,Cyborg Superman...) and he was also more popular among the people...
Conner has the chance to become as successfull as Flash,Wonder Woman etc. IF he can finally take the NIGHTWING step (new Code-Name, becoming older and getting an area of his own).
Conner works perfectly as the Nightwing of the Super-Family, he is the young,edgy,cool equivalent to Clark like Dick is to Bruce.
What he needs is:
1. To get portrayed as being competent and people also asking him etc. like its with Nightwing
2. also being able to argue etc. with the JL like Nightwing did when he asked for his team (saying that he doesnt ask for permission..)
and also be considered by the JL to lead Teams and being respected by them etc.
3. use his TT Power-Level and feats etc. BUT combine it with the coolness,groove etc. of the Kessel Hawaii Superboy
So for Jonathan Samuel Kent it should be like its for Tim Drake and Damian: you either go to Bruce(Clark) or to Dick(Conner)
Its the perfect solution, give Conner the Pre-Flashpoint History (with feats etc.) back and let him move to Hawaii, so he has freedom to develop and has an area of his own to protect and its like a PERFECT CIRCLE, he started in Hawaii and now he comes back.