OneToOne relationShip and number field type

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Hello Teams,
very strange, i have try many and many ..and Number (auto-increment) and don't understand :
entity : AA have oneToMany BB
entity : BB have oneToOne to CC, to DD, to EE

on a service, i create the entity AA ... number type field autoIncrement are not set !

$aa->set([ 'name' => $name ]);
 $entityManager->saveEntity($aa); 

aaNumberField is empty !?

in the same service : i create bb

$bb->set([
'name' => $patient->get('name') .' ' .$contact->get('name')  ]);
 $entityManager->saveEntity($bb); 

bbNumberField is set !

i relate bb to aa

$entityManager->getRepository('AA')->relate($aa, 'xyz', $bb); 

it's work .. oneToMany

and i try to relate some oneToOne on bb entity and

$entityManager->getRepository('bb')->relate($bb, 'xyzw', $cc); 

and only one bb is related ! (i think unique Id )

i have not find the right way to relate oneToOne and why aaNumberField is not set and bbNumberField is set :s
i use pdo to update in hard way..

For me, it's relate bb only one time to other entity.... but it's oneToOne.. then each bb have to be related.

I have no formula, no hook in these two entity..

Any helps

Regards