TS, are you even sure of your own and your wife's blood type first?

Go and check if you really want to make sure.

3rd possibility, either you or your wife have chimerism.

It is possible with chimerism (if TS has a twin) or microchimerism (if TS has no twin).

Well you can check, one sperm sample and one blood sample. Microchimerism is where the fetus exchanges bloodtypes with the mother (though the incidence of this type is quite rare). As for primary chimerism, I'm too uncertain of your family's medical history to make an educated guess.

For twins, the incidence of chimerism is moderate.

This idiot never bothered to check his own blood type 100%.

I guarantee he simply said B+ to the Doctor because he didn't know.

This is a simple case of bodo.