would the children of a green opaline cock and yellow face opaline hen be only green or would there be some yellow faces there as well

you have not said what colour the yf hen is

it is a yellow face blue with yellow all through her wings the black markings are very faint

Kaz for the question the colour of the hen doesn't matter. (grey or blue)

 

Only green offspring unless the cock is split for blue.

 

Do you have pictures? an opaline yellowface blue will have the body colour on the wings not yellow. Sounds like you either have a spangle or greywing depending on what you mean as "faint"