Sorry for just getting back, it's been a crazy week! Hard to tell the sex on your birds from the pictures posted...I can't enlarge them on my phone. Have you tried vent sexing?
As far as breeding them, there are numerous routes you could take. It all depends your goals for the next generations...
SF Silver can be visually sexed. Things get tricky when Silver is combined with other mutations. Charcoal (silver Tibetan) would be an example of a combination mutation that cannot be reliably visually sexed.
I'd love to see your Silvers if you have any pics!