You are technically correct but some of your genes are off. All color genes have two halves. Blue is Bl/bl, Columbian is Co/Co, etc. So instead of Co/Splash (the gene that is responsible for Splash and Blue coloration is called Blue, not Splash) it would be written as Co/Co Bl/bl (Blue Mille Fleur) and Co/White would be written as Co/Co I/I (True Golden Neck).
Also, I had the genes wrong for Lavender, lol. A porcelain is lav/lav, not Lav/Lav, as Lavender is recessive.
The colors below are all "Gold-Based" and are all genetically e+/e+ (Wildtype) s/s (Gold) Ig/Ig (Recessive Cream) Co/Co (Columbian) mo/mo (Mottled) Rb+/Rb+ (Recessive Black) i/i (Dominant White). Unless you are breeding to a color that is not listed below, then you don't need to worry about these genes as they are all the same. The differences between these varieties is caused by the differences in the blue and lavender genes that are listed beside of them.
Millie Fleur - bl/bl (Blue) Lav/Lav (Lavendar)
Porcelain - bl/bl lav/lav
Blue Mille Fleur - Bl/bl Lav/Lav (Not to be confused with the Blue/Blue Mottled color D'uccle, which is Black-Based)
Splash "Golden Neck" - Bl/Bl Lav/Lav (True Golden Neck is based on Dominant White Gene I/I. I do believe it is a Gold-Based color as well but I don't see the genes for it on the source I am using so I will not list it here.)
To get blue you will need to breed in the Blue gene. Since Porcelain is a Lavender-based color that does not carry the Blue gene, breeding Porcelain with Mille Fleur will not accomplish this.
Splash "Golden Neck" (Bl/Bl) x Mille Fleur (bl/bl) = 100% Blue Mille Fleur
Splash "Golden Neck" (Bl/Bl) x Blue Mille Fleur (Bl/bl) = 50% Splash, 50% Blue Mille Fleur
Blue Mille Fleur (Bl/bl) x Mille Fleur (bl/bl) = 50% Mille Fleur, 50% Blue Mille Fleur
Blue Mille Fleur (Bl/bl) x Blue Mille Fleur (Bl/bl) = 25% Splash, 50% Blue Mille Fleur, 25% Mille Fleur
You can also use Porcelains in place of the Mille Fleurs on this chart. The only difference is that the offspring will be split for Lavender (Lav/lav) and you will be able to breed more Porcelains by breeding these Lav/lav birds together or back to another Porcelain.
I would never advise breeding a non-gold based bird, such as a black, to a gold-based because it would take many generations to get the colors pure again.
Source:
http://www.edelras.nl/belgians/genetics.htm