Welsh Harlequin Sex & Colour Phase

[Waddlewoods]

My ducklings are nearly 7 weeks old and I'm thinking I have a male & female based off of colour & quack. The darker head I'm assuming is a Drake and has a raspy voice and the lighter one has a very noisy quack.
My question is how reliable is that at this age? I had a runner duckling (same age) who was quacking at 5 weeks but now has a raspy voice. When are their voices permanent?

Also, am I right in thinking these are silver phase WH?

 

[cheezenkwackers]

I think you have a male and female Silver phase, just like you thought. By this age the quack doesn’t change. Your female looks very similar to the one I had.

Mine got lighter as she aged.

 

[Waddlewoods]

She's beautiful!! Thank you for the response!
I've noticed that they really stick together. I also have 4 runners the same age but the 2 welshies are inseparable.