Opaline fallow bourke grass parakeets

Understanding genetics of mutations, in this case, for bourkes is one thing, but putting it into practice can sometimes be a little tricky.  One of the more confusing mutations in grasskeets is the fallow mutations of the bourkes.  It's been said there may be at least 3 different fallow mutations - all of which are autosomal recessive (both males and females need 2 copies of the to show the mutation and so both genders can be splits).  Dun fallow is suppose to be the darkest with dark grey nails.  Bronze fallow is a bit lighter in coloration with pale fallow being the lightest.  When the fallow mutation is combined with the opaline, it can be very difficult to tell what kind of fallow the "pink" or opaline fallow bird is. 

opaline fallows: male on left, hen on right

Case and point: I put together a pair of pink bourkes - both are opaline fallows.  Both having pretty light faces and clear nails, I thought perhaps both are pale fallow opalines.  However, all their 4 babies are dark eyed rosies or appear to be regular opalines.  This means they are all opaline split to 2 different kinds of fallows because the father and mother must be 2 different kinds of fallows.  Some more expert breeders feels perhaps the male is a bronze fallow opaline but due to the effect of the opaline gene, the nail color became completely clear.

male opaline fallow - ?bronze fallow

hen opaline fallow - probably pale fallow

4 opaline split to bronze and pale fallows