ha ha adding silver you mean adding in the LAVENDER BECAUSE HE IS NOT LAVENDER. Based on your posts on your profile your an novice chicken breeder so call me when you graduate with a genetic degree. Last time I'm saying this "self blue". Have a great life!
You can add 2 copies of Lavender to anything. Yes, it is technically a lavender if it has 2 copies, but, if you happen to have autosomal red in the mix, or gold base, you will get the leakage, it's a Lavender with leakage. I concentrate on type over color, color is easy. TYPE makes the breed.
By breeding to a silver based Lavender, or Black split with silver, it's quite simple to only use the chicks that hatch out grey and grey with white bellies. Any yellow down and there's gold or autosomal red in there, no bueno.
The Black splits I used for that batch had autosomal red, but instead of losing a year of breeding over a minor flaw, I chose to progress with the better "type". Color will be cleaned up this fall, or next spring, no big deal.
You can call that bird Lavender all you want, it's Blue. I mean no disrespect saying that, and never did, it has excellent lacing and looks to be growing nicely.