No lavendar aka porcelain will not show with only one lav. Crossing lav to any Dom color should make X split to porcelain.
The chicken calculator goes screwy with lavs and self blues on a lot of breeds.
So to make more Lavs when you only have on Lav hen or roo the crossing would go as...
We are all at the mercy of our information, unless anyone happens to be a geneticist which i will be happy to admit i am far from lol.
As for the no buff mottled in the US....i will tell you a secret lol. Buff Mottleds are in the US, a Golden Neck is a Buff Mottled.
Buff Mottled is Mille Fluer...
You would get a bunch of white birds split to Lav.
Lavendar is 2 Recessive
White is 1 Dom 1 Recessive
If you bred the white to the lav, then bred your F1 white split to Lav birds back to the Lav parent you would make Porcelains.
F1 bred back results: 50% White split to Lav 50% Porcelain
If...
Golden necks will not give you a mottled blue unless they are those from such places as ideal or ideal lineage because ideal does not seperate all their birds for breeding in the D'uccle line. In fact they put non-like together, as in Black and White D'uccles in one pen, Golden neck and Blue in...